1
down(adjective, hard, evil, rough, nasty)
1
exploiting(adjective, dishonest, immoral, rotten, untrustworthy)
1
extortionate(adjective, dishonest, immoral, rotten, untrustworthy)
1
false-principled
1
falsified
1
fast and loose(expression, adjective, idiom, dishonest, immoral)
1
faulty
1
fixed(adjective, dishonest, immoral, rotten, untrustworthy)
1
flagitious
1
foresworn(adjective, false, fickle, untrue, untrustworthy)
1
formidable(adjective, hard, evil, rough, nasty)
1
forsworn(adjective, mean, bad, base, false)
1
gone to the dogs(expression, adjective, idiom, dishonest, immoral)
1
hard(adjective, evil, rough, nasty, rude)
1
hard-nosed(adjective, hard, evil, rough, nasty)
1
hellish
1
heretical
1
hollow(wrong, false, dishonest, deceitful, incorrect)
1
ignoble(adjective, hard, evil, rough, nasty)
1
ill-natured(adjective, malevolent)
10 years ago|17k views|share |citing 
APASmart Define. (2016). perfidious thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/perfidious/thesaurus/synonyms
ChicagoSmart Define. 2016. "perfidious thesaurus" https://smartdefine.org/perfidious/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2016, perfidious thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/perfidious/thesaurus/synonyms>.
MLASmart Define. "perfidious thesaurus" 4 March 2016. Web. 24 September 2026. <https://smartdefine.org/perfidious/thesaurus/synonyms>