Synonyms for Grim:

adj.

all (adjective)
relentless, unforgiving, stern, inexorable, unappeasable, unrelenting.
bad (adjective)
gloomy.
dejected (adjective)
despairing, heartbroken, sullen, moody, mournful, anguished, melancholy, anxious, sad, blue, dispirited, pensive, contemplative, overcome, lachrymose, woeful, morose, joyless, plaintive, dejected, dolorous, downhearted, depressed, miserable, disconsolate, disheartened, glum, wistful, despondent, gloomy, discouraged, dreary.
depressed (adjective)
morose.
grisly (adjective)
grisly.
hopeless, horrible in manner, appearance (adjective)
crabbed, morose, crusty, cantankerous, ghastly, stubborn, glum, churlish, grumpy, austere, grisly, intractable, gruesome, severe, sulky, splenetic, forbidding, relentless, terrible, hideous, bleak, sour, harsh, grouchy, somber, horrid, stern, glowering, gloomy, implacable, unrelenting, scowling, surly, inexorable, sullen.
serious (adjective)
earnest, sedate, sober, demure, solemn, somber, intense, dignified, grave.
severe (adjective)
stringent, oppressive, exacting, acerbic, sharp, dour, unbending, hard, strait-laced, piquant, chilly, acute, uncompromising, rigorous, ascetic, relentless, puritanical, draconian, critical, tart, astringent, lean, disciplined, brusque, authoritarian, bleak, acrimonious, imperial, fundamental, cutting, keen, harsh, raw, inflexible, crisp, stark, prudish, dry, abrupt, hidebound, short, cool, spartan, strict, basic, frosty, austere, precise, blunt, rigid, severe, obdurate, stiff-necked, correct, intense, caustic, obstinate, gruff, icy, demanding, meticulous, stern, censorious, spare, brisk, curt, intolerant.
sullen (adjective)
frowning, unfriendly, sour, crabby, grumpy, scowling, fretful, contrary, sulky, mean, long-faced, surly, dark, cantankerous, petulant, noncooperative, uncooperative, broody, glowering, ungenial, malevolent, beetle-browed, Moping, cross, unsociable, grouchy, cynical, hostile, dissociable, irascible.

n.

painful, unhappy, terrible, heartbreaking, tragic, upsetting. driven, die-hard, ambitious, unbendable, uncompliant, competitive, Incompliant, purposeful, iron, sedulous, resist, dedicated, remorseless, insistent, stubborn, motivated, brassbound. hot, angry, belligerent, hard, irritated, upset, attitude, put out, annoyed, displeased. frail, unhealthy, beautiful, horrible, lurid, horrid, infectious, failing, unwell, worse, fragile, unfit, hideous. disagreeable, awful, objectionable. unappealing, unattractive, ugly, monstrous, grotesque, unsightly, plain. grim (noun)
disconsolate, grisly, sarcastic, dismal, inexorable, dispiriting, unappeasable, gruesome, hopeless, dour, gloomy, mordant, ghastly, implacable, forbidding, alarming, cheerless, stern, blue, unforgiving, depressing, relentless, unpleasant, macabre, unrelenting, dark, uncheerful, black.
relentless (noun)
wicked.
unfriendly (noun)
antagonistic, cold, stony, aloof, distant.

Other synonyms:

unappealing, Incompliant, unbendable, brassbound, unsightly, uncompliant. grotesque, stubborn, lurid, die-hard, monstrous, unattractive. horrible, hideous, ugly. horrid, iron. plain. catastrophic
tragic.
relentless
remorseless.
Other relevant words:
die-hard, depressing, ugly, hard, sarcastic, hideous, horrible, forbidding, cheerless, unpleasant, churlish, awful, inexorable, wicked, horrid, aloof, splenetic, alarming, mordant, plain, crusty, unbendable, unrelenting, repellent, painful, gruesome, ghastly, unappealing, implacable, lurid, grisly, unhappy, iron, tragic, dismal, terrible, uncheerful, unforgiving, intractable, unappeasable, grotesque, stony, monstrous, unattractive, dispiriting, Incompliant, uncompliant, stubborn, hopeless, black, unsightly, macabre, remorseless, cold, crabbed, brassbound.

Usage examples for grim

  1. " Robbery," he repeated, with a glance at Casavel and Caterina, who stood one on each side of the table that bore such a grim burden, and looked at each other. – Tomaso's Fortune and Other Stories by Henry Seton Merriman
  2. But the boy looked up at her with grim mouth and hard eyes. – Frank of Freedom Hill by Samuel A. Derieux
  3. It was a grim fight, down there in the dark! – The Boy With the U.S. Miners by Francis Rolt-Wheeler