c. 1300, "bondsman; common man, man of low birth," from Old Norse karl "man" (as opposed to "woman"), "male, freeman," from Proto-Germanic *karlon- (source also of Dutch karel "a fellow," Old High German karl "a man, husband"). The same Proto-Germanic source produced Old English ceorl "man of low degree" (see churl) and the masc. proper name Carl and, via French and Latin, Charles.
The Mellere was a stout carle for the nones [Chaucer]