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

Treason is the only crime defined in the U.S.

From Slate • Nov. 21, 2025

That man, Marcus Sarjeant, was charged and convicted under the Treason Act.

From New York Times • Feb. 3, 2023

Treason carries a sentence of up to 20 years in jail.

From Reuters • Oct. 10, 2022

Jaswant Singh Chail appeared via video-link to face three charges, including an offence under the Treason Act.

From BBC • Oct. 5, 2022

I telephoned Winnie the next day at the hospital and asked her for help in raising money for the Treason Trial Defense Fund from the Jan Hofmeyr School.

From "Long Walk to Freedom" by Nelson Mandela

Related Words

• crime
• mutiny
• sedition
• subversion
• treachery