extremity vs chelicera

extremity and chelicera both are nouns.

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

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

extremity: an external body part that projects from the body
chelicera: either of the first pair of fang-like appendages near the mouth of an arachnid; often modified for grasping and piercing

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

extremity (noun)	chelicera (noun)
an external body part that projects from the body	either of the first pair of fang-like appendages near the mouth of an arachnid; often modified for grasping and piercing
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)