giant cockroach vs roach

giant cockroach and roach both are nouns.

Word	Noun	Adjective	Verb	Adverb
giant cockroach	Yes	No	No	No
roach	Yes	No	Yes	No

As nouns, roach is a hypernym of giant cockroach; that is, roach is a word with a broader meaning than giant cockroach:

Other hypernyms of giant cockroach include cockroach.

giant cockroach (noun)	roach (noun)
large tropical American cockroaches	any of numerous chiefly nocturnal insects; some are domestic pests
	European freshwater food fish having a greenish back
	the butt of a marijuana cigarette
	street names for flunitrazepam
	a roll of hair brushed back from the forehead

giant cockroach (verb)	roach (verb)
	cut the mane off (a horse)
	comb (hair) into a roach