Meaning

adjective not to be placated or appeased or moved by entreaty

adjective shockingly repellent; inspiring horror

adjective harshly ironic or sinister

originFrom Middle English grim, grym, greme, from Old English *grimu, *grimmu, grima, from Proto-Germanic *grimmį̄ (“anger, wrath”), from Proto-Indo-European *gʰrem- (“to resound, thunder, grumble, roar”). Cognate with Middle Dutch grimme, Middle High German grimme f (“anger”), modern German Grimm m.

Etymology from Wiktionary, CC BY-SA 3.0