The ineffective and inconsistent use of terminology among fire managers, scientists, resource managers and the public is a constant problem in resource management. In fire management and fire science, the terms fire severity, burn severity and fire intensity are defined in a variety of ways, used inconsistently and, in some cases, interchangeably. This problem has become more apparent as the use of these terms has increased, partly because: 1) The occurrence of large wildfires, especially in the wildland-urban interface, has engaged many interest groups and citizens in discussions concerning fuel treatments, fire management and fire suppression; 2) The passage of the Healthy Forest Restoration Act emphasizes the need for understanding wildland fire risk; and 3) The addition of funding through the Joint Fire Sciences Program and the National Fire Plan has enabled the scientific community to conduct an increasing number of studies on fire behavior and effects and has increased the use of fire as a management tool. As a result, fire severity, burn severity and fire intensity are terms used in discussions, presentations, publications and meetings where people of widely different backgrounds are exchanging information, ideas and making decisions.