grimly /ˈɡɹɪmli/adjective 1adverb 1forms 4 adjective1 •(no longer used) Grim-looking, grim-natured. adverb1 •In a grim manner.He looked round and shouted grimly, "As soon as the gate is opened, you go out there - running." — 1966 formsgrimlier · more grimly · grimliest · most grimly