(a.) Without conscience; indifferent to conscience; unscrupulous.

conscienceless corrupt corrupted criminal crooked dark devious dishonest dishonorable doubtful dubious evasive felonious fishy fraudulent ill-got ill-gotten immoral indirect insidious nonmoral not kosher questionable rotten shady shameless shifty sinister slippery steeped in vice suspicious tricky unconscienced unconscientious unconscionable underhand underhanded unethical unmoral unprincipled unsavory unscrupulous unstraightforward vice-laden vice-prone vicious without remorse without shame