attacker vs piranha

attacker and piranha both are nouns.

Word	Noun	Adjective	Verb	Adverb
attacker	Yes	No	No	No
piranha	Yes	No	No	No

As nouns, piranha is a hyponym of attacker; that is, piranha is a word with a more specific, narrower meaning than attacker:

attacker (noun)	piranha (noun)
someone who attacks	small voraciously carnivorous freshwater fishes of South America that attack and destroy living animals
	someone who attacks in search of booty