noun.
A compulsive disorder characterised by obsession with fire or uncontrollableurges to start fires.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
an uncontrollable desire to set fire to things
Word Usage
"At one time it was assumed that there was a mental disorder known as pyromania; the pyromaniac was one with an irresistible impulse to light incendiary fires."