huitre vs shellfish

huitre and shellfish both are nouns.

Word	Noun	Adjective	Verb	Adverb
huitre	Yes	No	No	No
shellfish	Yes	No	No	No

As nouns, shellfish is a hypernym of huitre; that is, shellfish is a word with a broader meaning than huitre:

huitre: edible body of any of numerous oysters
shellfish: meat of edible aquatic invertebrate with a shell (especially a mollusk or crustacean)

huitre (noun)	shellfish (noun)
edible body of any of numerous oysters	invertebrate having a soft unsegmented body usually enclosed in a shell
	meat of edible aquatic invertebrate with a shell (especially a mollusk or crustacean)