extremity vs mouthpart

extremity and mouthpart both are nouns.

Word	Noun	Adjective	Verb	Adverb
extremity	Yes	No	No	No
mouthpart	Yes	No	No	No

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

extremity: an external body part that projects from the body
mouthpart: any part of the mouth of an insect or other arthropod especially one adapted to a specific way of feeding

Other hyponyms of extremity include chelicera, fang, chela, claw, nipper, pincer, parapodium, fin, pleopod, swimmeret, limb, dactyl, digit.

extremity (noun)	mouthpart (noun)
an external body part that projects from the body	any part of the mouth of an insect or other arthropod especially one adapted to a specific way of feeding
that part of a limb that is farthest from the torso
the outermost or farthest region or point
the greatest or utmost degree
an extreme condition or state (especially of adversity or disease)