WordReference Random House Unabridged Dictionary of American English © 2024fire•bug (fīər′bug′),USA pronunciation n. [Informal.]- Informal Termsarsonist;
incendiary;
pyromaniac.
- fire + bug1 1870–75, American.
Collins Concise English Dictionary © HarperCollins Publishers::
firebug /ˈfaɪəˌbʌɡ/ n - informal a person who deliberately sets fire to property