Accelerants. Materials, usually flammable liquids, used to initiate or increase the spread of fire.

Aerial fire apparatus.  A fire truck equipped with an aerial ladder that brings firefighters, water or equipment to higher levels, and also provides a means of escape from upper stories

Aerial ladder. A power-operated ladder permanently mounted on a piece of apparatus.

All hands. A working fire at which all units of the first alarm assignment are engaged in firefighting.

Apparatus. A motor-driven fire truck or a collective group of such trucks.

Arson. The crime of willfully burning one’s own or another’s property.

Authority having jurisdiction. A term used in many standards and codes to refer to the organization, office, or individual responsible for approving equipment, procedures and construction in a town, county, city or state.


Backdraft. The explosion of heated gases that occurs when oxygen is introduced into a space within a burning building where the oxygen has been depleted by the fire.

Basic life support. Noninvasive emergency life-saving care to treat airway obstruction, cardiac arrest or respiratory arrest.

Battalion chief.  The lowest ranking chief officer, also called district chief. These chiefs are often in charge of running calls and supervising multiple stations or districts within a city. A battalion chief is usually the officer in charge of a single-alarm working fire.

Bunker coat, bunker pants. The protective coat and trousers worn by a firefighter for interior structural firefighting. Also called turnout coat and turnout pants.


Captain. The second ranking officer, between the lieutenant and battalion chief. Captains are often in charge of a company or fire station.

Carbon monoxide. A toxic gas, odorless and colorless, that produced when substances are incompletely burned.

Combustible. Capable of reacting with oxygen and burning if ignited.

Commission on Fire Accreditation International. A nonprofit organization that accredits fire and emergency service agencies.

Company officer. The captain or lieutenant, or occasionally sergeant, who is in command of a  team of firefighters, both on scene and at the station.

Conduction. Heat transfer within an item or from one to another by direct contact.

Convection. Heat transfer by circulation within a gas or liquid.


Egress.  A way out or exit.

Emergency medical technician (EMT).  A professional who provides prehospital care for people who are sick or injured, including transport, medication and the use of defibrillators. EMTs have differing levels of training:

EMT -Basic. An emergency medical technician trained in basic emergency care skills, including oxygen therapy, bleeding control, cardiopulmonary resuscitation, automated external defibrillation, use of basic airway devices, and assisting patients with certain medication. Most EMTs fall into this category.

EMT – Intermediate. An emergency medical technician trained to do EMT-Basic care, plus IV therapy, interpretation of cardiac rhythms, defibrillation, and airway intubation.

EMT – Paramedic. An emergency medical technician with the most advanced training, capable of cardiac monitoring, administering drugs, inserting advanced airways, manual defibrillation, and other advanced assessment and treatment skills.

Engine company. A group of firefighters responsible for securing a water source, deploying hose lines, conducting search-and-rescue operations, and putting water on the fire.


Fire code. A set of legally adopted rules and regulations designed to prevent fires and protect lives and property.

Fire devil. A small, burning cyclone that results when heated gases from a fire rise and cooler air rushes into the resulting areas of low pressure; usually occurs during forest and brush fires but also in free-burning structural fires.

Fire hook. A tool to pull down burning structures; used in Colonial times as the only way to stop a fire.

First responder. The first trained person to arrive at the scene of an emergency  to provide initial medical assistance.

Flameover (rollover). The rapid spread of flame over surfaces.

Flammable.  Capable of being readily ignited.

Flashover.  The stage of fire when all surfaces and objects are heated to their ignition temperature (flash point) and flame breaks out almost at once over the entire surface.

Flash point. The lowest temperature at which a liquid or solid releases enough vapor to ignite when mixed with air.


Head of the fire. The main or running edge of a fire, the part of the fire that spreads fastest.


IDLH: Immediate Danger to Life and Health. An atmospheric concentration of any toxic, corrosive or asphyxiant substance that poses an immediate threat to life or could cause irreversible or delayed harm to health. There are three IDLH atmospheres: toxic, flammable and oxygen-deficient.

Ignition point. The minimum temperature at which a substance will burn.

Ignition temperature. The minimum temperature at which a fuel, whe heated, will ignite in air and continue to burn; the minimum temperature required to for a self-sustained combustion.

Incendiary fire. An intentionally set fire.

Incident Management System. A management structure that can be quickly adapted to any situation, a standard approach with predefined roles, responsibilities, procedures and terminology.

Initial attack vehicle.  A small fire truck, like a pumper but with less capacity to pump water.

ISO or Insurance Services Office. An organization that gathers information about risk for the insurance industry, including ratings of fire departments’ abilities to suppress a fire.


Lieutenant. A company officer who is usually responsible for a single fire company on a single shift; the first in line of company officers, in command when the captain is absent.

Life Safety Code.  NFPA 101, the code that describes the structures, equipment and behaviors that can protect life if there is a fire, such as size and location of exits and the need for regular fire drills.

Life safety rope. Rope used solely for the purpose of supporting people during firefighting, rescue, other emergency operations and training.

Line.  One or more lengths of connected hose.


Mayday. Code that indicates a firefighter is lost, missing or requires immediate assistance.


National Fire Incident Reporting System, or NFIRS System.  A system by which fire departments provide computerized records of fires and other fire department incidents in a uniform manner.


Oxidation. A chemical reaction in which an element combines with oxygen. All fires are a form of oxidation.


PASS. Personal alert safety system. Device worn by a firefighter that sounds an alarm if the firefighter is motionless for a period of time.

Paramedic. An emergency medical technician (EMT) with the highest level of level of training.  Most EMTs are not paramedics, so the terms should not be used interchangeably. Paramedics are trained to do cardiac monitoring, administer drugs, insert advanced airways, perform manual defibrillation, and conduct other advanced assessments and treatments.

Personnel accountability system. A method of tracking the identity, assignment, and location of firefighters operating at an incident scene.

Positive pressure ventilation. The practice of forcing contaminated air out of burning building by placing a blower in the doorway and blowing the air through a ventilation hole cut in the roof..

PPE. Personal protective equipment. The helmet, hood, coat, gloves, self-contained breathing apparatus and boots worn by firefighters to protect against heat and water.

Products of combustion. Heat, smoke and toxic gases.

Pumper.  A fire truck capable of forcing out at least 750 gallons of water per minute, with a hose at least 1,000 feet long, and a water tank holding at least 300 gallons. Some also have foam-making systems to smother flammable-liquid fires, or to make a different type of foam that reduces the surface tension of water so it penetrates more quickly.

Pyrolysis. The chemical decomposition of a compound into one or more other substances by heat alone; pyrolysis often precedes combustion.


Quint. A fire truck that has an aerial ladder as well as pump, hose, tank and ladders.


Radiation. Heat transfer through electromagnetic waves, without objects or gases carrying it along. Radiated heat goes out in all directions, unnoticed until it strikes an object.

Respirator. A maskworn over the mouth and nose to filter smoke and fumes from the air.

Response time. The time a fire company takes to get to a fire and begin fire operations.

RIC. Rapid intervention company/crew. A minimum of two firefighters who stand by at a fire, fully equipped and ready, to rescue injured or trapped firefighters.

Rollover. The rapid spread of flame over surfaces (also called flameover).


Self-contained breathing apparatus (SCBA). Respirator with independent air supply used by firefighters to enter toxic and otherwise dangerous atmospheres.

Staging area. A strategically located area where support personnel, vehicles, and other equipment can be held in an organized state of readiness for use during an emergency.


Tanker. A fire truck designed to carry water to fires, usually 1,000 gallons or more;  it is also equipped with a pump.

Thermal column. A cylindrical area above a fire in which heated air and gases rise and travel upward. The magnitude and intensity of a fire can often be judged from the thermal column.

Thermal imaging device. An electronic device that detects differences in temperature based on infrared energy and then generates images based on that data. Commonly used in obscured environments to locate victims.

Turnout coat and pants. The protective coat and trousers worn by a firefighter for interior structural firefighting. Also called bunker coat and bunker pants.


Under control. The stage of a fire at which it has been partially extinguished and authorities are confident can be completely extinguished.

Utility rope. Rope used for securing objects, hoisting equipment, or blocking access to a scene. It is never to be used to support people.


Wildland. Land in an uncultivated natural state that is covered by trees, brush, weeds or grass.

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