Similar word to underhand:
clandestine, concealed, crafty, crooked, cunning, deceptive, devious, dirty-dealing, dishonest, dishonorable, double-crossing, duplicitous, fraudulent, furtive, guileful, hush-hush, indirect, insidious, oblique, on the QT, on the quiet, secret, secretive, shady, shifty, slippery, sly, sneaking, sneaky, stealthy, sub-rosa, surreptitious, treacherous, tricky, two-faced, two-timing, under wraps, undercover, underhanded, unethical, unfair, unjust, unscrupulous, wily
clandestine, concealed, crafty, crooked, cunning, deceptive, devious, dirty-dealing, dishonest, dishonorable, double-crossing, duplicitous, fraudulent, furtive, guileful, hush-hush, indirect, insidious, oblique, on the QT, on the quiet, secret, secretive, shady, shifty, slippery, sly, sneaking, sneaky, stealthy, sub-rosa, surreptitious, treacherous, tricky, two-faced, two-timing, under wraps, undercover, underhanded, unethical, unfair, unjust, unscrupulous, wily
