Underhand

Adjective

1. secret; clandestine
2. (by extension) dishonest and sneaky; done in a secret or sly manner
3. (in various ball games, of a ball) thrown (etc.) with the hand brought forward and up from below

Synonyms

• (all): underhanded
• (ball games): underarm

Adverb

1. with an underhand movement
2. in a sly, sneaky or secret manner

Synonyms

• (in a secret manner): underhandedly