adjective, verb, adverb · stylish, hip, or fashionable (loanword from English)

他今天穿得真酷。

noun, adjective · cruel, oppressive, or merciless

这种古代的法律极其严酷。

noun · very potent or intense, particularly in reference to wine or weather

正当酷暑，大家都在树下乘凉。