boxfish vs plectognath

boxfish and plectognath both are nouns.

Word	Noun	Adjective	Verb	Adverb
boxfish	Yes	No	No	No
plectognath	Yes	No	No	No

As nouns, plectognath is a hypernym of boxfish; that is, plectognath is a word with a broader meaning than boxfish:

boxfish: any of numerous small tropical fishes having body and head encased in bony plates
plectognath: tropical marine fishes having the teeth fused into a beak and thick skin covered with bony plates or spines

Other hypernyms of boxfish include plectognath fish.

boxfish (noun)	plectognath (noun)
any of numerous small tropical fishes having body and head encased in bony plates	tropical marine fishes having the teeth fused into a beak and thick skin covered with bony plates or spines