From Wiktionary, the free dictionary
From កាច (kaac, “fierce, ferocious”) with infixed -Vmn- (resultative).
កំណាច • (kɑmnaac)
- cruelty, brutality
- wildness, savagery, barbarity
- a mean, cruel or evil person
កំណាច • (kɑmnaac) (abstract noun ភាពកំណាច)
- to be cruel, brutal, savage, wicked, vicious