1781, back-formation of sulky (adj.). Related: Sulked; sulking. As a noun from 1792.
Entries linking to sulk
sulky adj.
"quietly sullen," 1744, of uncertain origin. Connection has been suggested to obsolete, rare sulke "hard to sell" (1630s) and to Old English asolcen "idle, lazy, slow," past-participle adjective from aseolcan "become sluggish, be weak or idle" (related to besylcan "be languid"), from Proto-Germanic *seklan (source also of Middle High German selken "to drop, fall"). But words of similar meaning often are held to be imitative (compare miff, mope, boudoir). Related: Sulkily; sulkiness.