bombshell vs bomb

bombshell and bomb both are nouns.

Word	Noun	Adjective	Verb	Adverb
bombshell	Yes	No	No	No
bomb	Yes	No	Yes	No

As nouns, bomb is a hypernym of bombshell; that is, bomb is a word with a broader meaning than bombshell:

bombshell (noun)	bomb (noun)
an explosive bomb or artillery shell	an explosive device fused to explode under specific conditions
a shocking surprise	strong sealed vessel for measuring heat of combustion
an entertainer who has a sensational effect	an event that fails badly or is totally ineffectual

bombshell (verb)	bomb (verb)
	throw bombs at or attack with bombs
	fail to get a passing grade