Definitions for "Underhand"
Secret; clandestine; hence, mean; unfair; fraudulent.
By secret means; in a clandestine manner; hence, by fraud; unfairly; dishonorably.
Done, as pitching, with the hand lower than the shoulder, or, as bowling, with the hand lower than the elbow.
In an underhand manner; thrown with the hand no higher than the shoulder and the palm turned upward during part of the pitch; -- said of pitching or bowling a ball.
with hand brought forward and up from below shoulder level; "an underhand pitch"; "an underhand stroke"
Keywords:  oldline, slyly, donne, bowers, revenge
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
Where excavation is carried downslope from access level (see cut and fill)
marked by deception; "achieved success in business only by underhand methods"