Where does “ác như hùm” come from?

ác như hùm (Vietnamese) comes from Vietnamese ác, from Proto-Vietic ʔaːk, from Proto-Mon-Khmer kʔaak — crow; to caw.

Ancestry of “ác như hùm”, step by step

ác như hùm traces back through 3 separate lines of ancestry.

via Vietnamese ác

StepLanguageWordMeaning
1Vietnameseáccruel; evil; inhumane; merciless; savage; evil
2Proto-Vieticʔaːkcrow
3Proto-Mon-Khmerkʔaakcrow; to caw

via Vietnamese như

StepLanguageWordMeaning
1Vietnamesenhưlike; as
2Middle Chinese如—

via Vietnamese hùm

StepLanguageWordMeaning
1Vietnamesehùmtiger
Every word from Proto-Mon-Khmer kʔaak →Every word from Proto-Vietic ʔaːk →Every word from Vietnamese ác →
ác như hùm — Etymology, Origin & Word History | Etymology Explorer