noun
heinousness; ferocity
Rare literary term for extreme cruelty or brutal fierceness. Not used in everyday speech; found mainly in older or formal writing.
その犯罪の凶悍さは、人々を震え上がらせた。
The heinousness of the crime made people shudder.
彼の目には凶悍な光が宿っていた。
A ferocious light dwelled in his eyes.
凶悪 is a common word for 'heinous' or 'atrocious', used in modern contexts like 凶悪犯罪 (heinous crime). 凶悍 is a rare, literary synonym with a stronger nuance of brutal fierceness.
残忍 means 'cruel' or 'brutal' and is more common than 凶悍. 凶悍 emphasizes a wild, fierce cruelty rather than cold-bloodedness.
Composed of 凶 (bad luck, evil) and 悍 (fierce, brutal). The exact historical derivation is uncertain; the spelling is conventionally associated with extreme cruelty.