treason

American  

[tree-zuhn] / ˈtri zən /

noun

1. the offense of acting to overthrow one's government or to harm or kill its sovereign.

2. a violation of allegiance to one's sovereign or to one's state.

3. the betrayal of a trust or confidence; breach of faith; treachery.

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treason British  

/ ˈtriːzən /

noun

1. violation or betrayal of the allegiance that a person owes his sovereign or his country, esp by attempting to overthrow the government; high treason

2. any treachery or betrayal

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Related Words

Treason, sedition mean disloyalty or treachery to one's country or its government. Treason is any attempt to overthrow the government or impair the well-being of a state to which one owes allegiance; the crime of giving aid or comfort to the enemies of one's government. Sedition is any act, writing, speech, etc., directed unlawfully against state authority, the government, or constitution, or calculated to bring it into contempt or to incite others to hostility, ill will or disaffection; it does not amount to treason and therefore is not a capital offense. See disloyalty.

Other Word Forms

• supertreason
  noun
• treasonable
  adjective
• treasonableness
  noun
• treasonably
  adverb

Etymology

Origin of treason

First recorded in 1175–1225; Middle English tre(i)so(u)n, from Anglo-French; Old French traïson, from Latin trāditiōn-, stem of trāditiō “delivery, transfer, betrayal”; see tradition

Compare meaning

How does treason compare to similar and commonly confused words? Explore the most common comparisons:

• sedition vs. treason

Explanation

Hacking your brother’s email account and sharing all his secrets with your mom could be considered an act of personal treason, meaning you have betrayed your brother. The word treason can be traced back to the Latin word traditio(n-), which comes from the verb tradere, meaning "to hand over, betray." If you commit treason, that’s what you do: you betray. The word is typically used to refer to the betrayal of a government or a country, like when a spy shares national secrets with another country, but it can be used to refer to personal betrayals as well.

Example Sentences

Similarly, the earl of Peterborough's son refused both to remove his hat and to enter a plea when tried for treason in 1658.

From Science Daily • May 7, 2026

The UN rights chief said Friday he was "deeply concerned" by a Cambodian court rejecting the appeal of detained opposition leader Kem Sokha against his nearly three-decade sentence for treason.

From Barron's • May 1, 2026

Tundu Lissu is still in detention on treason charges, which he denies, while Luhaga Mpina's candidacy was rejected on technical grounds.

From BBC • Apr. 23, 2026

They repeatedly moved to dismiss the treason count, noting that conviction required a “breach of allegiance, and can be committed by him only who owes allegiance either perpetual or temporary.”

From Slate • Apr. 2, 2026

In 1894, the French criminologist Bertillon had helped to wrongfully convict Alfred Dreyfus of treason, having presented a wildly incorrect handwriting analysis.

From "Killers of the Flower Moon" by David Grann

Related Words

• crime
• mutiny
• sedition
• subversion
• treachery