Which term refers to a fire that spreads rapidly with a well-defined head?

The term that refers to a fire spreading rapidly with a well-defined head is running. In wildland fire terminology, a "running fire" describes a fire that is moving quickly, typically characterized by a distinct front or head that advances rapidly. This type of fire behavior is often influenced by environmental factors such as wind speed, topography, and fuel type, allowing it to spread fast and cover large areas in a short amount of time.

Creeping describes a slower-moving fire that typically does not extend too far from the ground level, whereas spotting involves burning embers being carried away from the main fire to start new fires ahead of the main front. Crowning refers to fire moving through the canopy of trees, which can occur in certain conditions but does not specifically denote the rapid spread and distinct head associated with a running fire.