adjective (grimmer, grimmest)

forbidding or uninviting:

〈人･様子などが〉険しい, 厳格な; 〈決意などが〉断固とした, 不屈の

e.g. his grim expression

〈場所･建物などが〉不快な, 気のめいる, 醜い

e.g. long rows of grim, dark housing developments.

(of humor) lacking genuine levity; mirthless; black:

〖通例名詞の前で〗気味の悪い, ぞっとする〈笑顔など〉

e.g. some moments of grim humor.

depressing or worrying to consider:

〈状況･知らせなどが〉厳しい; 残酷な, 容赦ない; 〈事実などが〉厳然とした

e.g. the grim news of the murder.

unrelentingly harsh; merciless or severe:

e.g. few creatures are able to thrive in this grim and hostile land.

British with great determination:

e.g. we had to hold on like grim death.

grimness |ˈɡrimnəs| noun

Old English, of Germanic origin; related to Dutch grim and German grimm.