unfaithful

adjective

un·​faith·​ful ˌən-ˈfāth-fəl 

: 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

ˌən-ˈfāth-fə-lē 

adverb

unfaithfulness noun

Synonyms

• disloyal
• faithless
• false
• fickle
• inconstant
• perfidious
• recreant
• traitorous
• treacherous
• untrue

Examples of unfaithful in a Sentence

colonists who later proved to be unfaithful to the cause of independence

Recent Examples on the Web

But a president who commits a crime is unfaithful to both, because crimes are committed with corrupt motives. —Stephen Woolpert, The Mercury News, 3 Oct. 2024

But if former Gilmore Girls writer and consulting producer Stan Zimmerman had been in Netflix's writers room, Czuchry's character might not have followed that unfaithful path. —Zoey Lyttle, People.com, 3 Oct. 2024

Some of the men have been described as egocentric, aggressive, and routinely unfaithful. —Sophie Gilbert, The Atlantic, 3 Oct. 2024

For instance, consider someone who discovers their partner has been unfaithful. —Mark Travers, Forbes, 27 Sep. 2024

Word History

First Known Use

15th century, in the meaning defined above

Kids Definition

unfaithful

adjective

un·​faith·​ful ˌən-ˈfāth-fəl 

ˈən-

1

: not observing vows, allegiance, or duty : disloyal

an unfaithful friend

2

: not faithful to marriage vows

3

: inaccurate

an unfaithful translation

unfaithfully

-fə-lē 

adverb

unfaithfulness noun