The Oxford Thesaurus An A-Z Dictionary of Synonyms - grimadj.

1) stern, severe, unrelenting, resolute, uncompromising, unyielding, inflexible, adamant, stony, iron, unbending, firm, intractable, unflinching, unmoving, unmoved, implacable, inexorable, determined, steadfast, (dead) set, fixed, decided, obstinate, headstrong, stubborn, obdurate, dogged, unwavering: By controlling the purse strings, she kept a grim hold over the family. 2) forbidding, formidable, harsh, ferocious, fierce, cruel, savage, merciless, heartless, ruthless, pitiless, vicious, brutal, brutish, feral, inhuman, fiendish, violent, bloodthirsty, murderous, homicidal, fell: A grim pack of howling wolves loped after our sledge. 3) dire, dreadful, ghastly, awful, frightful, frightening, sinister, hideous, horrid, horrific, horrible, horrendous, terrible, terrifying, terrific, harrowing, dread, alarming, appalling, grotesque, gruesome, eerie, macabre, flagitious, heinous, evil, wicked, iniquitous, atrocious, monstrous: Before me appeared the ghostly apparition of the Grim Reaper.