Fire Glossary

A wildland firefighter wearing a blue fire pack suppresses a fire using a firehose.
Wildland fire has its own set of complex terminology used throughout all fire management activities.


This is a list of wildland fire terminology used throughout Isle Royale National Park's webpage. For more information, see the complete Glossary of Wildland Fire Terminology, published by the National Wildfire Coordinating Group.



A fire set along the inner edge of a fireline to consume the fuel in the path of a wildfire or change the direction of force of the fire's convection column.



Sudden increase in fireline intensity or rate of spread of a fire sufficient to preclude direct control or to upset existing suppression plans.


Burning Conditions

The state of the combined factors of the environment that affect fire behavior in a specified fuel type.



The status of a wildfire suppression action signifying that a control line has been completed around the fire, and any associated spot fires, which can reasonably be expected to stop the fire’s spread.


Creeping Fire

Fire burning with a low flame and spreading slowly. Also known as smoldering.

Crown Fire

A fire that advances from top to top of trees or shrubs more or less independent of a surface fire.

Defensible Space

The buffer between a building and the grass, trees, shrubs, or any wildland area that surround it. This space is needed to slow or stop the spread of wildfire and it helps protect structures from catching fire—either from embers, direct flame contact or radiant heat.


Fire Behavior

The manner in which a fire reacts to the influences of fuel, weather, and topography.

Fire Camp

A geographical site(s), within the general incident area, separate from the incident base, equipped and staffed to provide sleeping, food, water, and sanitary services to incident personnel.


Fire Dependent

Plants and vegetation communities which have evolved adaptations such as a reliance on fire as a disturbance agent, protection as a species against the effects of wildland fire, or even a strengthening or enhancement by it.


Fire Ecology

The study of the effects of fire on living organisms and their environment.

Fire Effects

The physical, biological, and ecological impacts of fire on the environment.


Fire Management

Activities required for the protection of burnable wildland values from fire and the use of prescribed fire to meet land management objectives.


Fire Management Unit

A land management area definable by objectives, management constraints, topographic features, access, values to be protected, political boundaries, fuel types, major fire regime groups, etc. that set it apart from the characteristics of an adjacent FMU. The FMU may have dominant management objectives and pre-selected strategies assigned to accomplish these objectives.



The part of a containment or control line that is scraped or dug to mineral soil.



The relative ease with which fuels ignite and burn regardless of the quantity of the fuels.



Easily ignitable and capable of burning and producing flames.


Fuel Management

Act or practice of controlling flammability and reducing resistance to control of wildland fuels through mechanical, chemical, biological, or manual means, or by fire, in support of land management objectives.



Any combustible material, especially petroleum-based products and wildland fuels.


Hot Spot

A particularly active part of a fire.


Humidity Recovery

The change in relative humidity over a given period of time; generally between late evening and sunrise. The fuel moisture change during this period is directly related to the amount of humidity recovery.


Incident Commander

This position is responsible for overall management of the incident and reports to the Agency Administrator for the agency having incident jurisdiction. This position may have one or more deputies assigned from the same agency or from an assisting agency(s).



A person designated to detect and report fires from a vantage point.


Lookout Tower

Also known as fire tower. Structure that elevates a person above nearby obstructions to sight for fires; generally capped by some sort of house or cupola.


Maintenance Burn

In prescribed fire terminology, a fire used to dispose of scattered, piled, or windrowed dead woody fuel, generally in the absence of a merchantable overstory. Its purpose is to reduce unsightly fuel concentrations, or consume unwanted natural fuels to facilitate subsequent resource management or land use actions on the area.


Marine Inversion

Temperature inversion produced when cold marine air underlies warmer air.


Mop Up

Extinguishing or removing burning material near control lines, felling snags, and trenching logs to prevent rolling after an area has burned, to make a fire safe, or to reduce residual smoke.


Natural Disturbance Agent

Agents of regeneration and restoration in an ecosystem, such as wildfire, wind, insect epidemics, etc.


Prescribed Fire

Any fire ignited by management actions to meet specific objectives. A written, approved prescribed fire plan must exist, and NEPA requirements (where applicable) must be met, prior to ignition.


Relative Humidity

The ratio of the amount of moisture in the air, to the maximum amount of moisture that air would contain if it were saturated. The ratio of the actual vapor pressure to the saturated vapor pressure.


Single Engine Airtanker (SEAT)

The smallest airtanker. These aircraft can deliver up to 800 gallons fire retardant or water to wildland firefighters on the ground. They are ideal for wildfires in lighter fuels like grasses and sagebrush.


Spot Fire

Fire ignited outside the perimeter of the main fire by a firebrand, or ember.



All the work of extinguishing or confining a fire beginning with its discovery.



The burning of the foliage of a single tree or a small group of trees, from the bottom up.


Wildland Urban Interface (WUI)

The line, area, or zone where structures and other human development meet or intermingle with undeveloped wildland or vegetative fuels.


Last updated: September 13, 2023

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