What does "perfidiousness" mean?

Unfaithfulness; deceitfulness; perfidy.

Perfidiousness

Q: What is a synonym for "perfidiousness"?

Common synonyms include: perfidy, treachery, betrayal, breach of promise, breach of trust, conspiracy.

noun

noun ·Uncommon ·Advanced level

Definitions

Noun

1
Unfaithfulness; deceitfulness; perfidy. rare, uncountable, usually
"Not only Cato is vanquished by Caesar, but the treachery and perfidiousness of Syphax prevail over the honest simplicity and the credulity of Juba."
2
betrayal of a trust wordnet

Synonyms

All synonyms

perfidy treachery betrayal breach of promise breach of trust conspiracy

Example

More examples

"Patriotism, often a thinly veiled form of collective self-worship, celebrates our goodness, our ideals, our mercy and bemoans the perfidiousness of those who hate us."

Etymology

From perfidious + -ness.

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.