Antonyms of adj underhand

2 senses of underhand

Sense 1
underhand (vs. overhand), underhanded, underarm -- (with hand brought forward and up from below shoulder level; "an underhand pitch"; "an underhand stroke")

overhand (vs. underhand), overhanded, overarm -- (with hand brought forward and down from above shoulder level; "an overhand pitch"; "an overhand stroke")
        => round-arm -- (with the arm swung round at shoulder height; "round-arm bowling")

Sense 2
sneaky, underhand, underhanded -- (marked by deception; "achieved success in business only by underhand methods")

INDIRECT (VIA crooked) -> straight, square -- (characterized by honesty and fairness; "straight dealing"; "a square deal")

Similarity of adj underhand

2 senses of underhand

Sense 1
underhand (vs. overhand), underhanded, underarm -- (with hand brought forward and up from below shoulder level; "an underhand pitch"; "an underhand stroke")

Sense 2
sneaky, underhand, underhanded -- (marked by deception; "achieved success in business only by underhand methods")
       => crooked (vs. straight), corrupt -- (not straight; dishonest or immoral or evasive)

Synonyms of adv underhand

2 senses of underhand

Sense 1
underhandedly, underhand -- (slyly and secretly; "Mean revenge, committed underhand"- John Donne; "oldline aristocratic diplomats underhandedly undermined the attempt...to align Germany with the Western democracies"- C.G.Bowers)

Sense 2
underarm, underhand -- (with the hand swung below shoulder level; "throwing a ball underarm")