- astute, sharp, shrewd - marked by practical hardheaded intelligence; "a smart businessman"; "an astute tenant always reads the small print in a lease"; "he was too shrewd to go along with them on a road that could lead only to their overthrow"
Antonym: stupid (indirect, via smart)
- calculating, calculative, conniving, scheming, shrewd - used of persons; "the most calculating and selfish men in the community"
Antonym: soft (indirect, via hard)