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.