unfaithful

adjective

un·​faith·​ful ˌən-ˈfāth-fəl How to pronounce unfaithful (audio)
: not faithful:
a
: not adhering to vows, allegiance, or duty : disloyal
an unfaithful friend
b
: not faithful to marriage vows
suspected her husband of being unfaithful
c
: inaccurate, untrustworthy
an unfaithful copy of a document
unfaithfully adverb
unfaithfulness noun

Examples of unfaithful in a Sentence

colonists who later proved to be unfaithful to the cause of independence
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Vajiralongkorn divorced their mother in 1996 after accusing her of being unfaithful, stripping her and their sons of their titles and forbidding their return to Thailand. Charlie Campbell, Time, 26 June 2025 People who worked on the nighttime emergency schedule were almost 18 times more likely to be unfaithful to their partners than those who worked part-time. Mark Travers, Forbes.com, 26 June 2025 Indeed, to rule otherwise would be unfaithful to the judgment and vision of the Founding Fathers! Sonam Sheth, MSNBC Newsweek, 2 June 2025 But understanding what drives a person to be unfaithful can offer clarity, closure, and even a starting point for healing. Jenna Ryu, SELF, 11 June 2025 See All Example Sentences for unfaithful

Word History

First Known Use

15th century, in the meaning defined above

Time Traveler
The first known use of unfaithful was in the 15th century

Browse Nearby Words

Cite this Entry

“Unfaithful.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unfaithful. Accessed 3 Jul. 2025.

Kids Definition

unfaithful

adjective
un·​faith·​ful ˌən-ˈfāth-fəl How to pronounce unfaithful (audio)
ˈən-
1
: not observing vows, allegiance, or duty : disloyal
an unfaithful friend
2
: not faithful to marriage vows
3
: inaccurate
an unfaithful translation
unfaithfully adverb
unfaithfulness noun

More from Merriam-Webster on unfaithful

Last Updated: - Updated example sentences
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