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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Synonym Usage

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
• treasonableness
  noun
• treasonable
  adjective
• 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

See Examples For:

treason

There were shouts of treason, but Gen. Washington intervened on Willing’s behalf, calling him a “worthy, well-disposed man.”

From The Wall Street Journal ● Jul. 17, 2026

He was found guilty of high treason under martial law and the illegal handling of weapons, ammunitions or explosives by the Shevchenkivskyy District Court in Kyiv.

From BBC ● Jun. 26, 2026

Cambodia's acting head of state, former prime minister Hun Sen, pardoned opposition leader Kem Sokha on Monday from a sentence of almost three decades for treason.

From Barron's ● May 25, 2026

Congress long had forfeiture rules in place for members who engaged in espionage, treason or other national-security offenses.

From The Wall Street Journal ● May 14, 2026

“Sins of the Father,” which was about Worf going back home to face accusations that his father had committed treason.

From "Darius the Great Is Not Okay" by Adib Khorram

Related Words

• crime
• mutiny
• sedition
• subversion
• treachery