late 14c., "one of two things at the extreme ends of a scale," from Old French estremite (13c.), from Latin extremitatem (nominative extremitas) "the end of a thing," from extremus "outermost;" see extreme, adj., the etymological sense of which is better preserved in this word. Meaning "utmost point or end" is from c.1400; meaning "limb or organ of locomotion, appendage" is from early 15c. (compare extremities). Meaning "highest degree" of anything is early 15c. Related: Extremital.