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perfidiousness

noun

Unfaithfulness; deceitfulness; perfidy.

Similar

double-dealing treachery treacherousness betrayal breach of promise breach of trust Judas kiss perfidy

Scrabble 20

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Meanings

nounperfidiousness (usually uncountable, plural perfidiousnesses)

plural perfidiousnesses

rareuncountableusuallyUnfaithfulness; deceitfulness; perfidy.
Not only Cato is vanquished by Caesar, but the treachery and perfidiousness of Syphax prevail over the honest simplicity and the credulity of Juba.
1781, Samuel Johnson, “Addison”, in Lives of the Poets
Synonyms: double-dealing, treachery, treacherousness, betrayal, breach of promise, breach of trust, double-dealing, Judas kiss

Synonyms & antonyms

nounUnfaithfulness; deceitfulness; perfidy.

Similar

double-dealing treachery treacherousness betrayal breach of promise breach of trust double-dealing Judas kiss perfidy prodition Punic faith stab in the back swike tergiversation traitory treacherousness treachery treason

More synonyms by meaning

nounbetrayal of a trust

Similar

perfidy treachery

Broader

Also see

betrayal double-dealing judas kiss perfidy prodition punic faith stab in the back swike tergiversation traitory treacherousness treachery treason

Synonym sets from Open English WordNet, CC BY 4.0.

Origin

From perfidious + -ness.

Full word history & related roots →

Cite this entry

APA

perfidiousness. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/perfidiousness

MLA

“perfidiousness.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/perfidiousness. Accessed November 2, 2026.

Chicago

WatkinsX Dictionary, s.v. “perfidiousness,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/perfidiousness.

Source: perfidiousness on Wiktionary, CC BY-SA 4.0.