extremity vs digit

extremity and digit both are nouns.

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

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

extremity: an external body part that projects from the body
digit: a finger or toe in human beings or corresponding body part in other vertebrates

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

extremity (noun)	digit (noun)
an external body part that projects from the body	a finger or toe in human beings or corresponding body part in other vertebrates
that part of a limb that is farthest from the torso	one of the elements that collectively form a system of numeration
the outermost or farthest region or point	the length of breadth of a finger used as a linear measure
the greatest or utmost degree
an extreme condition or state (especially of adversity or disease)