His perfidious actions betrayed the trust of everyone in the organization.
Synonyms for perfidious
traitorous
deceitful
treacherous
Antonyms for perfidious
loyal
faithful
true
Practice perfidious on real SAT questions
Vocabulary like perfidious appears on the Digital SAT in Words-in-Context questions, where you choose the word that fits a passage's meaning and tone. You can also drill this word with vocabulary flashcards.