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1. Not to be placated, appeased or moved by entreaty
   "grim determination"; "grim necessity";
   - inexorable, relentless, stern, unappeasable, unforgiving, unrelenting
    
2. Shockingly repellent; inspiring horror
   "the grim aftermath of the bombing";
   - ghastly, grisly, gruesome, macabre, sick
    
3. Harshly ironic or sinister
   "a grim joke"; "grim laughter";
   - black, mordant
    
4. Harshly uninviting or formidable in manner or appearance
   "a grim man loving duty more than humanity"; "undoubtedly the grimmest part of him was his iron claw";
   - dour, forbidding
    
5. Filled with melancholy and despondency
   "took a grim view of the economy";
   - gloomy, blue [informal], depressed, dispirited, down, downcast, downhearted, down in the mouth, low, low-spirited
    
6. Causing dejection
   "grim rainy weather";
   - blue [informal], dark, dingy, disconsolate, dismal, gloomy, sorry, drab, drear, dreary

Derived forms: grimmest, grimmer

See also: alarming, cheerless, dejected, depressing, implacable, sarcastic, sarky [Brit, informal], uncheerful, unpleasant

Encyclopedia: Grim, Patrick