[ uhn-feyth-fuhl ]
See synonyms for unfaithful on Thesaurus.com
  1. not faithful; false to duty, obligation, or promises; disloyal: Given how unfaithful the party has been to voters, it would be surprising if they won.

  2. not sexually loyal to a spouse or lover; adulterous: She was concerned her husband would be unfaithful when he travelled.

  1. not accurate or complete; inexact: The book was an unfaithful translation of the original.

  2. Obsolete. without religious faith; unbelieving.

Origin of unfaithful

First recorded in 1350–1400; Middle English unfeithful, unfaithful; un-1 + faithful

Other words for unfaithful

Other words from unfaithful

  • un·faith·ful·ly, adverb
  • un·faith·ful·ness, noun

Words Nearby unfaithful

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use unfaithful in a sentence

British Dictionary definitions for unfaithful


/ (ʌnˈfeɪθfʊl) /

  1. not true to a promise, vow, etc

  2. not true to a wife, husband, lover, etc, esp in having sexual intercourse with someone else

  1. inaccurate; inexact; unreliable; untrustworthy: unfaithful copy

  2. obsolete not having religious faith; infidel

  3. obsolete not upright; dishonest

Derived forms of unfaithful

  • unfaithfully, adverb
  • unfaithfulness, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012