The variability of firefighter jargon should not be taken as a rule; some terms are fairly universal (e.g. stand-pipe, hydrant, chief). But keep in mind that any term defined here may be department, or region, specific, or at least more idiosyncratic than you may realize.
Contents: Top - 0–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
- Above-ground storage tank: Storage tank that is not buried. Compare Underground storage tank. Unburied tanks are more prone to physical damage, and leaks are released to the air or ground, rather than the soil surrounding a buried tank.
- Accelerant: flammable fuel (often liquid) used by some arsonists to increase size or intensity of fire. May also be accidentally introduced when HAZMAT becomes involved in fire.
- Accountability: The process of emergency responders (fire, police, SAR, emergency medical, etc...) checking into and making themselves announced as being on-scene during an incident to an incident commander or accountability officer. Through the accountability system, each person is tracked throughout the incident until released from the scene by the incident commander or accountability officer. This is becoming a standard in the emergency services arena primarily for the safety of emergency personnel. This system may implement a name tag system or personal locator device (tracking device used by each individual that is linked to a computer).
- AFA: Automatic Fire Alarm/Actuating Fire Alarm
- Aircraft Rescue and Firefighting (ARFF): a special category of firefighting that involves the response, hazard mitigation, evacuation and possible rescue of passengers and crew of an aircraft involved in an airport ground emergency.
- Alarm: (1) system for detecting and reporting unusual conditions, such as smoke, fire, flood, loss of air, HAZMAT release, etc; (2) a specific assignment of multiple fire companies and/or units to a particular incident, usually of fire in nature; (3) centralized dispatch center for interpreting alarms and dispatching resources. See fire alarm control panel.
- All companies working: Status report at fire scene indicating that available manpower is busy, and more resources may become necessary if incident is not controlled soon.
- Ammonium nitrate: component of ANFO; contents of two ships that exploded in Texas City Disaster, killing over 500 people, including all 28 volunteer firefighters at the scene.
- ANFO: Ammonium Nitrate Fuel Oil combination making a high explosive.
- Apparatus: A term usually used by firefighters describing a piece of equipment, usually a company vehicle.
- Arson: the crime of maliciously (or perhaps recklessly) setting fire to property, especially a dwelling. Punishable in various degrees, depending upon the circumstances. Occasionally occurs as a psychotic act of a mentally ill firefighter.
- Authority Having Jurisdiction (or AHJ): organization or agency with legal authority over a given type of incident (e.g., fire, EMS, SAR, arson, HAZMAT); may change or overlap as incident changes, as where fire becomes arson investigation once danger is over, or Motor Vehicle Accident becomes police business after vehicle extrication, fire, and HAZMAT issues are complete.
- Autoextended fire: structure fire that has gone out a window or other opening on one floor and ignited materials above, on another floor or other space (attic, *censored*loft).
- Available flow: total amount of water that can be put on a fire, depending upon water supply, pump size, hoses, and distance to the fire. IC must assess available flow to determine whether additional apparatus or streams are required. See Fire flow requirement.
- BA Set: Breathing Apparatus Set comprising of a face-mask and compressed air cylinder
- Backdraft: A fire phenomenon caused when heat and heavy smoke (unburned fuel particles) accumulate inside a compartment, depleting the available air, and then oxygen/air is re-introduced, completing the fire triangle and causing rapid combustion.
- Backfiring: A tactic used in wildland firefighting associated with indirect attack, by intentionally setting fire to fuels inside the control line. Most often used to contain a rapidly spreading fire, placing control lines at places where the fire can be fought on the firefighter's terms.
- Back burning: Australian term, for Backfiring, above.
- Backflow preventer: Automatic valve used in hose accessories to ensure water flows only in one direction. Used in permanent fire department connections (FDC) to sprinklers and dry standpipes, as well as portable devices used in firefighting.
- Backstretching- Doing a Fire to Hydrant procedure.
- Bank down: What the smoke does as it fills a room, banks down to the floor, creating several layers of heat and smoke at different temperatures -- the coolest at the bottom.
- Boiling liquid expanding vapor explosion (BLEVE): Explosion of a pressure tank containing an overheated material when the vapor expansion rate exceeds the pressure relief capacity (e.g., steam boiler or LPG tank). If the contents are flammable, the rapidly released vapor may react in a secondary fuel-air explosion.
- Bomber: Australian Term, for fixed wing fire-fighting aircraft. Also called "water bomber".
- Box (Alarm): A mailslot or other file system containing a notecard with a planned response to an incident type. For example, a reported structure fire on Some Road would be tagged with Box 6; the notecard in Box 6 would contain the list of apparatus from various fire stations that should be dispatched to that incident. Assigning Boxes to areas (or even specific structures) significantly facilitated the process of getting the right tools to the right place on the initial dispatch, and helped eliminate the guesswork of "which department has what" on the fire scene. Boxes later evolved to contain escalation procedures - on the "2nd alarm", the Box would contain the next group of apparatus from various fire stations, etc. Modern CAD systems now abstract the Box Alarm concept, and allow box definitions to be triggered based on arbitrary geographic area, time of day, incident type, weather, and any other planned situation. For a given hydranted area, the "Summer" box will contain the usual response of Engine, Truck, and Rescue companies. In the winter, however, the box may be modified (automatically, or manually) to include Water Tankers on the initial dispatch, to handle the case of frozen hydrants. The term "Box" comes from the fire alarm pull boxes that were commonplace in major cities for well over fifty years. This was a telegraph system that involved bells to ring out the box number. This system was in place from the 1920s (or earlier) to well into the 1960s and 1970s in some cities. Boston was one of the first (if not THE first) major U.S. Cities to have a telegraph alarm system. They installed it in 1852. The Boston Fire Department still uses this system of paper rolls and bells. The modern use of "box cards" based upon an imaginary box location for dispatch or move up is often known as the "Phantom Box System".
- Bus* another term for ambulance,
- Bushfire: Australian term, for Wildfire, below.
- Call Firefighter: In the U.S., call firefighters respond as needed on a part time basis to all types of emergencies. Call firefighters train with their local engine companies in their districts. Call firefighters are utilized in three different ways. “First Responder" call firefighter units, are those units that are staffed entirely by paid call firefighters. These firefighters respond to all emergency incidents within their jurisdictional areas and are supported by full-time companies from adjoining jurisdictions. "Supplemental" call firefighter units are those units that staff a second engine company from a station that is also staffed by a full-time company. These units respond to all multi-unit responses in their district, and cover the station when the career companies are committed. "Augmentation" call firefighters are assigned to an existing career company and respond directly to the scene to augment that company's staffing. See also Retained firefighter (U.K.)
- Career Firefighter: (U.S.) A person whose primary employment is as a firefighter for a municipality or other agency or company and who derives the majority of his earned income working in the fire service. See also Wholetime firefighter (U.K.)
- Charge a hose: To make water pressure available on a hose in final preparation for its use. This is done on the scene after the hose is deployed.
- Charged hose: A hose that is filled with water and pressurized; ready to use. This is done after the hose is deployed.
- Chauffeur: See Engineer.
- Chimney fire: Fast and intense fire in a chimney flue in which accumulated creosote and other combustion byproducts ignite.
- Class A: A fire involving combustibles such as wood, paper, and other natural materials. See Fire Classes.
- Class B: A fire involving hydrocarbons. See Fire Classes.
- Class C: An electrical fire. See Fire Classes.
- Class D: A fire involving metals, such as sodium, titanium, magnesium, potasium, uranium, lithium, plutonium and calcium. See Fire Classes.
- Class E (Europe/Australia): A composite Class A/Class B fire that is not also a Class C fire.
- Class F (Europe/Australia): See Class K.
- Class K: A fire involving cooking oils. Technically, this is a subclass of Class B. See Fire Classes.
- *censored*loft: structural space above ceiling and below rafters, often connecting adjacent occupancies and permitting fire to spread laterally, often unseen.
- Collapse zone: The area around a structure that would contain debris if the building were to collapse.
- Combustion:
- Company: two or more firefighters organized as a team, led by a fire officer, and equipped to perform certain operational functions. Compare with platoon and unit.
- Company officer - A fire officer, typically a lieutenant or captain, who leads a team of two or more firefighters in a company.
- Compartment Fire: An "Isolated" fire, or a fire which is "boxed in" or "closed off" from the rest of the structure. An example of this is a fire in a room where all the windows and doors are closed preventing the fire from spreading to other rooms.
- Confined space:
- Conflagration: a large, typically urban, fire involving numerous structures; loosely defined as enveloping an area equivalent to one or more square blocks. Compare with firestorm.
- Crash Tender: a pump capable of spraying foam used at airports.
- Crew Resource Management (CRM) - Training developed by NASA based on the concept that the primary cause of the majority of aviation accidents is human error and problems with interpersonal communication in particular. The training has been adapted for the fire service and teaches firefighters the correct way to question orders on an emergency scene. It also helps supervisors understand that the questioning of an order should not be interpreted as a threat to their authority.
- Cross lay: Arrangement of hose on a pumper such that it can be quickly unloaded from either side of the apparatus; often pre-connected to a pump outlet and equipped with a suitable nozzle. Also known as Mattydale Lay.
- Dalmatian: "Firehouse dog."
- Dead lay: A load of hose on a pumper, but not connected to a pump outlet. Often used for larger supply lines.
- Defensive Attack: A primarily exterior form of attack often used when fighting the fire directly or from within a structure is not feasible due to dangers from direct flame, heat, structural collapse or the presence of hazardous materials. Often structures which are fully involved are attacked defensively with the main goal being the protection of nearby exposures. This form of attack is far less effective than an Offensive or Direct attack.
- Deflagration: An explosion with a propagation front traveling at subsonic speeds, as compared to supersonic detonation.
- Direct attack: "Putting the wet stuff on the red stuff." A form of fire attack in which hoses are advanced to the fire inside a structure and hose streams directed at the burning materials.
- Discharge flow: The amount of water flowing from a fire hydrant when it is opened; compare to static flow and residual flow.
- Determinate A code given by dispatch (Alpha -Echo) showing the severity of a call and how you should respond.
- Dispatch: Refers to person or place designated for handling a call for help by alerting the specific resources necessary.
- Draft: The process of pumping water from a static source below the pump.
- Drills: training during which an emergency is simulated and the trainees go through the steps of responding as if it were a real emergency.
- Electrical fire: A fire in which the primary source of heat is electricity, resulting in combustion of adjacent insulation and other materials; may be hazardous to attempt to extinguish using water.
- EMS: Emergency medical service(s).
- Engine: A fire suppression vehicle that has a water pump and, typically, is designed to carry firehose and a limited supply of water.
- Engineer: A firefighter responsible for driving the engine to the scene of the call and operation of the pumps on an engine, to provide sufficient water to the firefighters on the hose. The term may be either a position title or a rank; usage varies among departments.
- Engine Company: A group of firefighters assigned to an apparatus with a water pump and equipped with firehose and other tools related to fire extinguishment.
- Engine house: [archaic] A firehouse housing an engine company.
- Engine pressure: The pressure in a fire hose measured at the outlet of the pump.
- Enhanced 9-1-1: Electronic system for automatic correlation of physical telephone lines with information about the location of the caller -- a useful tool for dispatchers when the caller has an emergency but cannot speak.
- Evacuation: Removal of personnel from a dangerous area, in particular, a HAZMAT incident, burning building, or other emergency. Also refers to act of removing firefighters from a structure in danger of collapsing.
- Evolution: Uniform sequence of practiced steps by squad carrying out common tasks such as selection and placement of ladders, stowing hoses in hose bed, putting hoses and tools into service in particular patterns; intended to result in predictability during emergencies.
- Exothermic reaction: Chemical reaction giving off heat in the process, such as combustion.
- Explorer: a young adult, between 14 and 21, who learns the basics of firefighting.
- Exposure: Property near fire that may become involved by transfer of heat or burning material from main fire, typically by convection or radiation. May range from 40 feet (12 m) to several miles, depending on size and type of fire or explosion.
- Exterior attack: A method of extinguishing a fire which does not involve entering the structure. Often used when so much of the building is involved in fire that there is little or no benefit to risking firefighter safety by inserting them into the structure. May be a temporary measure when there are not sufficient personnel on scene to form an entry team and a rescue team (to rescue the entry team). Also known as Surround and drown. Compare Interior attack.
- Extrication: removal of a trapped victim such as a vehicle extrication, confined space rescue, or trench rescue; sometimes using hydraulic spreader, Jaws of Life, or other technical equipment.
- ETOH: the chemical symbol for ethanol, or ethyl alcohol, also used to describe someone believed to be intoxicated.
- FAST (or F.A.S.T.): Firefighter Assist and Search Team (also called Rapid Entry Team or Rapid Intervention Team/Crew) — firefighters assigned to stand by for rescue of other firefighters inside a structure; an implementation to support the Two-in, two-out rule; may have specialized training, experience and tools. While all of these versions of the name for a firefighter rescue crew either have been used or continue to be used in several areas, the National Incident Management System (NIMS) has determined that Rapid Intervention Crew, ("RIC") will be the national term. Current U.S. federally mandated training programs are in the process of standardizing this and other terms under DHS and FEMA.
- FDC (Fire Department Connection): Location in which pumping apparatus hooks to a buildings standpipe and or sprinkler system. Usually a 3" female connection.
- Fire Break: Especially in hilly or mountainous areas, roads or paths cut through brush with a tractor, bulldozer or other construction equipment. The purpose of these is to have an area with no brush, and thus, no fuel, so that a fire will hopefully burn out rather than jumping to another area with brush. Also to ensure vehicular access to brush areas.
- Fire code ( Fire safety code): regulations for fire prevention and safety involving flammables, explosives and other dangerous operations and occupancies.
- Fire complex: (U.S. Complex fire) Area of fires - many of the areas have multiple fires with multiple fronts.
- Fire engineering: Scientific design of materials, structures and processes for fire safety
- Fire escape: A building structure arranged outside to assist in safe evacuation of occupants during an emergency; may connect horizontally beyond a fire wall or vertically to a roof or (preferably) to the ground, perhaps with a counter-weighted span to deny access to intruders.
- Fire Fighter Fatality Investigation and Prevention Program (FFFIPP) - Program administered by the National Institute for Occupational Safety and Health (NIOSH), a department of the Center for Disease Control (CDC). It performs independent investigations of firefighter fatalities in the United States, also referred to as line of duty deaths (LODD). The programs goals are: 1.) to better define the characteristics of line of duty deaths among firefighters, 2.) to develop recommendations for the prevention of deaths and injuries, and 3.) to disseminate prevention strategies to the fire service.
- Firefighter: People who respond to fire alarms and other emergencies for fire suppression, rescue, and related duties.
- Firefighter Assist and Search Team: See FAST.
- Fire flow: The amount of water being pumped onto a fire, or required to extinguish a hypothetical fire. A critical calculation in light of the axiom that an ordinary fire will not be extinguished unless there is sufficient water to remove the heat of the fire.
- Fireground: The operational area at the scene of a fire; area in which incident commander is in control. Also used as name of radio frequency to be used by units operating in the fireground, as in “Responding units switch to fireground.”
- Fire hazard: Materials, structures or processes that may result in creating a fire, permitting a fire to grow undetected, or preventing people from escaping a fire.
- Firehouse: Another term for Fire station. Where fire apparatus is stored and where full-time firefighters work.
- Fire hydraulics: The study of pumps, hoses, pipes, accessories and tools for moving water or other extinguishing agents from a water supply to a fire.
- Fire inspector: A person responsible for issuing permits and enforcing the fire code, including any necessary premises inspection, as before allowing (or during) a large indoor gathering.
- Fire line: A boundary of a fire scene established for public safety and to identify the area in which firefighters may be working.
- Fire load (Btu/sq ft): An estimate of the amount of heat that will be given off during ordinary combustion of all the fuel in a given space; e.g., a bedroom or a lumberyard.
- Fire marshal: Administrative and investigative office for fire prevention and arson investigation.
- Fire officer - See Company officer
- Fire point: temperature at which materials give off flammable gases that will sustain fire, typically higher than flash point. Temperature at flashover.
- Fire Police: Special constables attached to a fire department, tasked with ensuring the safety and security of emergency scenes as well as general assistance to the fire department and other agencies.
- Fire prevention: Fire safety; standards for minimizing fire hazards.
- Fire-resistant: Materials designed or treated to have an increased fire point.
- Firestorm: A conflagration of great enough proportions to noticeably create its own wind conditions.
- Fire tetrahedron: The fire tetrahedron is based on the components of igniting or extinguishing a fire. Each component represents a property necessary to sustain fire: fuel, oxygen, heat, and chemical chain reaction. Extinguishment is based upon removing or hindering any one of these properties.
- Fire triangle: Model for understanding the major components necessary for fire: heat, fuel and oxygen. See also fire tetrahedron for a more comprehensive model.
- Fire wall: Building structure designed to delay horizontal spread of a fire from one area of a building to another; often regulated by fire code and required to have self-closing doors, and fireproof construction.
- Fire warden:
- Fire watch: Fixed or mobile patrols that watch for signs of fire or fire hazards so that any necessary alarm can be quickly raised or preventive steps taken.
- Fit test: Periodic test of how well the facepiece of an SCBA fits a particular firefighter.
- Flameover: Also known as rollover. The ignition of heated fire gasses at the ceiling level only. While dangerous to firefighters, this is not as deadly as Flashover.
- Flammable range, limits: The percentage mixture of fumes with air that will sustain fire; outside the limits the mixture is either too lean or too rich to burn.
- Flash point: Lowest temperature at which a material will emit vapor combustible in air mixture. Higher than Flame point of same material.
- Flashover: simultaneous ignition of combustible materials in a closed space, as when materials simultaneously reach their fire point; may also result in rollover.
- Foam- Extinguishing agent formed by mixing foam concentrate with water and aerating the solution for expansion.
- Foam Concentrate- Raw foam liquid as it rests in it storage container before the introduction of water and air.
- Forcible entry: gaining entry to an area using force to disable or bypass security devices, typically using force tools, sometimes using tools specialized for entry (e.g., Halligan, K-tool).
- Forward lay: Procedure of stringing water supply hose from a water source toward a fire scene; compare with reverse lay.
- Freelancing: dangerous situation at an incident where an individual carries out tasks alone or without being assigned; violation of personnel accountability procedures.
- Friction loss: Reduction of flow in a firehose caused by friction between the water and the lining of the hose. Depends primarily upon diameter, type and length of hose, and amount of water (GPM) flowing through.
- Frontage: The size of a building facing a street.
- Fully involved: Term of size-up meaning fire, heat and smoke in a structure are so widespread that internal access must wait until fire streams can be applied.
- GPM: Gallons Per Minute or how many gallons are being pumped out of a piece of equipment every minute
- GPM method ("gallons per minute"): Calculation of how much water, in GPM, will be necessary to extinguish a given volume of fire, under the circumstances (e.g., fuel class, containment, exposures, etc.).
- Grease fire: A fire involving any manner of cooking oil or other flammable cooking or lubricating materials. Also known as a Class B, F or K fire.
- Goer: An incident with persons reported.
- Hazard: a source of danger of personal injury or property damage; fire hazard refers to conditions that may result in fire or explosion, or may increase spread of an accidental fire, or prevent escape from fire. Under worker safety and health regulations, employers have a general duty to provide a workplace free of hazards. See also fire prevention, and HAZMAT.
- Hard Line: A smaller hose about one inch in diameter used by firefighters to clean apparatus.
- HAZMAT: Hazardous materials, including solids, liquids, or gases that may cause injury, death, or damage if released or triggered.
- Head pressure: How the pressure of a water stream is measured. By measuring the 'breakover' point, the point where the water stream breaks apart and begins to fall back to the ground, of a stream of water aimed vertically into the air. This is typically done with a one inch diameter hose and a fixed nozzle. Therefore, if a water stream breaks over at 50 ft (15 m), then it is said the pump has 50 feet (15 m) of head pressure. Current measurements of pumping capacity are now in GPM, Gallons Per Minute.
- Helitack: A rotary winged (helicopter) fire-fighting aircraft, such as the Erickson Skycrane which can be modified to hold 2100 gallons (9500L) of water or retardant.
- High-pressure system: A supplemental pump system used to pressurize the water supply, sometimes used during a large fire, or whenever more than one hydrant is being used.
- High-rise building: Any building taller than three or four stories, depending upon local usage, requiring firefighters to climb stairs or aerial ladders for access to upper floors.
- High-rise pack: A shoulder load of hose with a nozzle and other tools necessary to connect the hose to a standpipe.
- Hotshot crew: An extensively trained group of approximately twenty people which specializes in wildfire suppression with little or no outside logistical support.
- Hot zone: contaminated area of HAZMAT incident that must be isolated; requires suitable protective equipment to enter and decontamination upon exit; minimum hot zone distance from unknown material with unknown release is 330 feet (United Nations Emergency Response Guidebook); surrounded by "warm zone" where decontamination takes place.
- IDLH: Any situation deemed Immediately Dangerous to Life and Health. More narrowly defined by OSHA. See main IDLH article. An area of maximum danger to firefighters.
- Incident Commander: The officer in charge of all activities at an incident. See Incident Command System.
- Incident Safety Officer: The officer in charge of scene safety at an incident. See Incident Command System.
- Indirect attack: Method of firefighting in which water is pumped onto materials above or near the fire so that the splash rains onto the fire, often used where a structure is unsafe to enter.
- Initial attack: First point of attack on a fire where hose lines or fuel separation are used to prevent further extension of the fire.
- Interface zone (also wildland/structural interface or urban/wildland interface): The zone where wildfires threaten structures or structural fires threaten wildlands, such as in residential areas adjacent to forests. This requires both wildland firefighting and structural firefighting in the same location, which involve very different tactics and equipment.
- Interior attack: Inserting a team of firefighters into the burning structure, in an attempt to extinguish a blaze from inside the structure, minimizing property damage from fire, smoke, and water. Requires a minimum of four fully-equipped firefighters: an entry team of at least two to enter the structure and fight the fire, and two standing by to rescue or relieve the entry team (see two in, two out). If the entry team(s) cannot extinguish the blaze, may become an Exterior Attack.
- ISO Rating: (Insurance Services Office Public Protection Classification Rating) This is a rating published by the Insurance Services Office. Insurance companies, in many states, use this number to determine homeowner insurance premiums. Recently some insurance companies, including State Farm, have now adopted a per-zip-code, actual loss, based system in several states and no longer use the ISO (PPC) system.
- Irons: The flathead axe mated with the halligan bar. Firefighters often refer to these as the Crossed Irons, or Married Irons, because the Halligan Bar can fit to the Axe head.
- Jumping-sheet: The sheet held by a group of firefighters on which people caught in a burning building can jump on to.
- Ladder company: A group of fire fighters, officers and engineers that staff a ladder truck.
- Level I, II, III Incident: A HAZMAT term denoting the severity of the incident and the type of response that may be necessary, where Level III is the largest or most dangerous.
- Life safety code: NFPA publication.
- Life line: A trademark for a wireless emergency call unit that triggers a telephone call to an emergency dispatcher when a button is pressed.
- Line loss: See friction loss.
- Live line: A fire hose under pressure from a pump. Also, an energized electrical line that may cause a hazard to firefighters.
- Loaded stream: An obsolete fire extinguisher stream that has had a chemical fire suppression agent added and is discharged by compressed gas or by inverting the tank to mix chemicals to produce gas pressure. Now outlawed by OSHA regulation 1910.157(c)(5). [Not to be confused with air pressurized water extinguishers with a Class A foam generating concentrate added at one-half of 1% by volume. Class A foam formed when mixed with air upon discharge produces surfactant-containing tiny bubbles which break surface tension to quickly penetrate and extinguish wood, paper, cloth and other common materials.]
- Make Pumps: To raise the number of pumps at an incident E.G. Make Pumps 10
- Maltese Cross: The emblem of the fire service is often referred to as a “Maltese Cross”. But the actual origin of the current or common emblem in the U.S. remains uncertain. While it is true that the Knights Hospitalers of Jerusalem (AKA Knights of St. John) did wear a cross emblem and a version of that cross has been used as a fire service icon, it bears little resemblance to the current form in use in much of the United States. It is possible to accept that the current design is just a stylized artistic embellishment of the original form. The current design may have also been influenced by the design of the cross of Saint Florian.
- Mass casualty incident (MCI): Any incident that produces a large number of injured persons requiring emergency medical treatment and transportation to a medical facility. The exact number of patients that makes an incident "mass casualty" is defined by departmental procedures and may vary from area to area.
- Master box: A primary fire alarm relay box connected to a building alarm system which monitors fire alarm pull stations and detectors throughout the building and automatically relays any in-building alarm to the local municipal fire department. Usually accompanied by an Annunciator Panel which records by indicator lights or other devices exactly where the pull station or detector that has been activated is located within the building. Common in multi-story office and apartment buildings equipped with sprinkler systems or smoke and heat detectors.
- Master stream: A large nozzle, either portable or fixed to a pumper, capable of throwing large amounts of water relatively long distances.
- Means of egress: The way out of a building during an emergency; may be by door, window, hallway, or exterior fire escape; local fire codes will often dictate the size. location and type according to the number of occupants and the type of occupancy.
- Multiple alarms: A request by an incident commander for additional personnel and apparatus. Each department will vary on the number of apparatus and personnel on each additional alarm.
- Mutual aid: An agreement between nearby fire companies to assist each other during emergencies by responding with available manpower and apparatus.
- MVA: Motor Vehicle Accident