Definition of grim

• not to be placated or appeased or moved by entreaty; "grim determination"; "grim necessity"; "Russias final hour, it seemed, approached with inexorable certainty"; "relentless persecution"; "the stern demands of parenthood"
• shockingly repellent; inspiring horror; "ghastly wounds"; "the grim aftermath of the bombing"; "the grim task of burying the victims"; "a grisly murder"; "gruesome evidence of human sacrifice"; "macabre tales of war and plague in the Middle ages"; "macabre tortures conceived by madmen"
• harshly ironic or sinister; "black humor"; "a grim joke"; "grim laughter"; "fun ranging from slapstick clowning ... to savage mordant wit"