Of forbidding or fear-inspiring aspect; fierce; stern; surly; cruel; frightful; horrible.
- Unrelenting; rigid.
- Uninviting or unnerving in aspect; forbidding: "undoubtedly the grimmest part of him was his iron claw” ( J.M. Barrie).
- Ghastly; sinister: "He made a grim jest at the horrifying nature of his wound” ( Reginald Pound). See Synonyms at ghastly.
- Dismal; gloomy: a grim, rainy day.
- Ferocious; savage: the grim advance of the pillaging army.