extremity vs fang

extremity and fang both are nouns.

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

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

extremity: an external body part that projects from the body
fang: an appendage of insects that is capable of injecting venom; usually evolved from the legs

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

extremity (noun)	fang (noun)
an external body part that projects from the body	hollow or grooved tooth of a venomous snake; used to inject its poison
that part of a limb that is farthest from the torso	canine tooth of a carnivorous animal; used to seize and tear its prey
the outermost or farthest region or point	an appendage of insects that is capable of injecting venom; usually evolved from the legs
the greatest or utmost degree
an extreme condition or state (especially of adversity or disease)