\Wild"fire\, n. 1. A composition of inflammable materials, which, kindled, is very hard to quench; Greek fire. Brimstone, pitch, wildfire . . . burn cruelly, and hard to quench. --Bacon. 2. (Med.) (a) An old name for erysipelas. (b) A disease of sheep, attended with inflammation of the skin. 3. A sort of lightning unaccompanied by thunder. [R.]