1) Clandestine or deceptive 2) Like some pitches 3) Marked by deception 4) Not open and aboveboard 5) Slyly and secretly 6) Sneaky 7) Surreptitious 8) Underarm 9) Underhanded 1) Crafty 2) Deceitful 3) Devious 4) Furtive 5) Hidden 6) Peon 7) Sneaky 8) Suspicious 9) Underarm 10) Underhanded 11) Underhandedly 
• (a.) Done, as pitching, with the hand lower than the shoulder, or, as bowling, with the hand lower than elbow. • (adv.) By secret means; in a clandestine manner; hence, by fraud; unfairly. • (a.) Secret; clandestine; hence, mean; unfair; fraudulent. • (adv.) In an underhand manner; -- said of pitching or bowling.Underhand: wor...
[adj] - (sports) with hand brought forward and up from below shoulder level
underhanded adjective with hand brought forward and up from below shoulder level; `an underhand pitch`; `an underhand stroke`
not open and aboveboard; secret and crafty or dishonorable: an underhand deal with the chief of police. · executed with the hand below the level of the shoulder and the palm turned upward and forward: an underhand delivery of a ball.