(a.) Being without principles; especially, being without right moral principles; also, characterized by absence of principle.

amoral conscienceless corrupt corrupted criminal crooked dark devious dishonest dishonorable dissolute doubtful dubious evasive felonious fishy fraudulent ill-got ill-gotten immoral indirect insidious licentious mercenary not kosher profligate questionable reprobate rotten shady shameless shifty sinister slippery stick-at-nothing suspicious tricky unconscienced unconscientious unconscionable underhand underhanded unethical unsavory unscrupulous unstraightforward venal without remorse without shame