perfidious

What does “perfidious” mean?

adjective.deceitful and untrustworthy.

SAT Usage

this term often appears in contexts involving betrayal, trust, or moral dilemmas, particularly in literary or historical passages. It emphasizes a deeper sense of betrayal and treachery, suggesting not just untrustworthiness but a calculated deceit, distinguishing it from similar words like "disloyal," which may not carry the same connotation of cunning or premeditated betrayal.

Common Confusions

Perfidious implies a calculated deceit and betrayal of trust, while treacherous usually suggests a betrayal that is more impulsive or reckless without the same level of premeditation.

Example Sentences

• The perfidious ally betrayed them on the eve of battle.

Word Parts: How to Remember “perfidious”

Break “perfidious” into its parts: per- (through, thoroughly) + -fid- (faith, trust). Knowing roots like these helps you decode unfamiliar SAT vocabulary.

• Prefix: per- through, thoroughly (Latin)
• Root: -fid- faith, trust (Latin)