Cunning or deceiving, not straightforward or honest, not frank.
Roundabout, circuitous, deviating from the direct or ordinary route.
Sly, dishonest, corrupt, cheating.
Done by moving the hand (and arm) from below.
Insincere; sarcastic.
An underhanded compliment is actually criticism.
Secret; surreptitious.
His underhanded trick backfired and he was disqualified.
Understaffed.
Devious people, collectively.
In an underhanded manner.