Word Origin & History
O.E. grimm "fierce, cruel," from P.Gmc. *grimmaz (cf. Ger. grimm, O.N. grimmr, Swed. grym "fierce, furious"), from PIE *ghrem- perhaps imitative of the sound of rumbling thunder (cf. Gk. khremizein "to neigh," O.C.S. vuzgrimeti "to thunder," Rus. gremet' "thunder"). A weaker word now than once it was;
sense of "dreary, gloomy" first recorded c.1175. It also had a verb form in O.E., grimman (class III strong verb; past tense gramm, p.p. grummen). O.E. also had a noun, grima "goblin, specter," perhaps also a proper name or attribute-name of a god, hence its appearance as an element in place names. As a noun meaning "a form of bogey or haunting spirit," first recorded 1628.