parapodium vs appendage

parapodium and appendage both are nouns.

Word	Noun	Adjective	Verb	Adverb
parapodium	Yes	No	No	No
appendage	Yes	No	No	No

As nouns, appendage is a hypernym of parapodium; that is, appendage is a word with a broader meaning than parapodium:

parapodium: one of a pair of fleshy appendages of a polychete annelid that functions in locomotion and breathing
appendage: an external body part that projects from the body

Other hypernyms of parapodium include extremity, member.

parapodium (noun)	appendage (noun)
one of a pair of fleshy appendages of a polychete annelid that functions in locomotion and breathing	a part that is joined to something larger
	an external body part that projects from the body
	a natural prolongation or projection from a part of an organism either animal or plant