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Definitions

unfaithful

[uhn-feyth-fuhl] / ʌnˈfeɪθ fəl /
ADJECTIVE
disloyal, adulterous
Synonyms
STRONGEST
cheating untrue
WEAK
adulterine deceitful double-crossing faithless false false-hearted fickle foresworn inconstant incontinent moonlighting not true to of bad faith perfidious philandering recreant shifty snaky sneaking traitorous treacherous treasonable two-faced two-timing unchaste unreliable untrustworthy wicked
Antonyms
WEAK
faithful loyal trustworthy

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Then there’s the Norwegian biathlete who admitted to being unfaithful in a very public bid for forgiveness.

From The Wall Street Journal • Feb. 13, 2026

"And three months ago, I made the biggest mistake of my life and I was unfaithful," he continued.

From Barron's • Feb. 11, 2026

The construction worker was filmed tearfully pleading: "I swear to God, I am being so straight... I have not been unfaithful to her."

From BBC • Sep. 10, 2024

The term “homewrecker” makes my skin crawl — probably because my dad was serially unfaithful to my mom, which I knew about for two reasons.

From Los Angeles Times • Mar. 22, 2024

Like Enrique’s mother, Eva was leaving an unfaithful husband.

From "Enrique's Journey" by Sonia Nazario