I. fire ‧ bomb 1 /ˈfaɪəbɒm $ ˈfaɪrbɑːm/ BrE AmE noun [countable]
a bomb that makes a fire start burning when it explodes
II. firebomb 2 BrE AmE verb [transitive]
to attack a place with firebombs:
His home was firebombed by animal rights activists.
—firebombing noun [uncountable]