deceiving, lying, untruthful, double-dealing, deceitful, fraudulent, false, counterfeit, cunning, crafty, sneaky, tricky, knavish, wily, crooked, deceptive, misleading, bluffing, evasive, slippery, unctuous, insincere, hypocritical, disingenuous, pettifogging, swindling, cheating, sneaking, recreant, roguish, backbiting, treacherous, falsehearted, traitorous, villainous, sinister, mendacious, duplicitous, perfidious, insidious, devious, Machiavellian, hoodwinking, underhanded, shady*, two-timing*, double, two-faced*, double-crossing*, fork-tongued*; see also false 1, hypocritical, mean 3.
Antonyms honest*, truthful, candid.
unprincipled, shifty, unscrupulous, undependable, disreputable, questionable, dishonorable, corrupt, immoral, unethical, untrustworthy, discredited, ignoble, unworthy, degraded, shabby, mean, low, venal, self-serving, contemptible, canting, corruptible, crooked, rotten*, dirty*, fishy*; see also sense 1; corrupt 1, false 1.
Antonyms scrupulous, trustworthy, ethical.
dishonest implies the act or practice of telling a lie, or of cheating, deceiving, stealing, etc. a dishonest official; deceitful implies an intent to make someone believe what is not true, as by giving a false appearance, using fraud, etc. a deceitful advertisement; lying suggests only the act of telling a falsehood curb your lying tongue; untruthful is used as a somewhat softened substitute for lying, esp. with reference to statements, reports, etc. an untruthful account