perfidious + -ness
perfidiousness (usually uncountable, plural perfidiousnesses)
- (rare) Unfaithfulness; deceitfulness; perfidy.
- 1781, Samuel Johnson, "Addison" in Lives of the Poets:
- Not only Cato is vanquished by Caesar, but the treachery and perfidiousness of Syphax prevail over the honest simplicity and the credulity of Juba.
- “perfidiousness” in Noah Webster, An American Dictionary of the English Language, volume II (J–Z), 1st edition, New York, N.Y.: Published by S. Converse; printed by Hezekiah Howe, New Haven, 1828, OCLC 999480247.
- perfidiousness in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913
- “perfidiousness” in Dictionary.com Unabridged, Dictionary.com, LLC, 1995–present.