1. (a.) Violating good faith or vows; treacherous; deceitful; faithless; as, a perfidious friend\.

2. (a.) Involving, or characterized by, perfidy.

Machiavellian alienated ambidextrous artful corrupt crafty crooked cunning deceitful disaffected dishonest disloyal double double-dealing double-faced double-minded double-tongued doublehearted duplicitous estranged faithless FALSE false-principled falsehearted hypocritical insidious mercenary recreant shifty slippery traitorous treacherous treasonable treasonous tricky two-faced unfaithful unloyal untrue venal