disloyal

American  

[dis-loi-uhl] / dɪsˈlɔɪ əl /

adjective

1. false to one's obligations or allegiances; not loyal; faithless; treacherous.

   Synonyms:

   treasonable, traitorous, perfidious, unfaithful

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disloyal British  

/ dɪsˈlɔɪəl /

adjective

1. not loyal or faithful; deserting one's allegiance or duty

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Other Word Forms

• disloyalist
  noun
• disloyally
  adverb

Etymology

Origin of disloyal

1470–80; < Middle French desloial, Old French desleal, equivalent to des- dis- ¹ + leal loyal

Explanation

If you're disloyal, you're not faithful or trustworthy — you can't be depended on by those who put their trust in you. It would be disloyal to join in with a group of people gossiping about your best friend. It's disloyal when a country violates a signed treaty, and it's disloyal for a citizen to spy for a foreign state against its own government. But it's also disloyal to betray the trust of someone in your life. A disloyal sibling tattles on his brothers and sisters, and a disloyal friend won't keep your secrets. This adjective comes from the Old French desloial, "treacherous or deceitful," which adds the prefix des-, "the opposite of," to loial, "faithful."

Example Sentences

But we find that these generations are particularly brand disloyal.

From Barron's • Apr. 9, 2026

They were trying to avoid seeming judgmental, unenlightened or disloyal to a socially expected script.

From The Wall Street Journal • Jan. 2, 2026

In turn, anyone who sides with their cause will be labeled a criminal enabler, a disloyal pariah.

From Los Angeles Times • Nov. 25, 2025

On July 31, 1395, the Duke of Burgundy declared a war of annihilation on an "evil and disloyal" enemy and invader: a purple, acidic grape known as "Gamay."

From Salon • Aug. 26, 2024

“Why are they so disloyal to King James?”

From "The Witch of Blackbird Pond" by Elizabeth George Speare

Related Words

• disaffected
• untrustworthy