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

That disloyal, greedy kid at the center of college football’s first apparent holdout?

From Los Angeles Times • May 1, 2026

But we find that these generations are particularly brand disloyal.

From Barron's • Apr. 9, 2026

The Labor Department will be ready to enforce the law if plan fiduciaries act with a disloyal motive or threaten the retirement security of American workers.

From The Wall Street Journal • Mar. 30, 2026

“I’ve never seen her be disloyal to the president,” Vance said.

From Salon • Dec. 16, 2025

To leave West Virginia, even to leave Welch, would have been unthinkably disloyal, like deserting your family.

From "The Glass Castle" by Jeannette Walls

Related Words

• disaffected
• untrustworthy