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

Copenhagen dismissed and charged Kauffmann with high treason, which he ignored.

From The Wall Street Journal • Apr. 11, 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

Ryan was tried alongside Azerbaijani citizen Azad Mamedli, who was convicted of high treason and sentenced to 12 years behind bars.

From Barron's • Mar. 16, 2026

The last was Charles I, who was arrested in 1646 and executed three years later for treason.

From Salon • Feb. 20, 2026

The newly reunified Federal Republic of Germany charged Markus Wolf with treason.

From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau

Related Words

• crime
• mutiny
• sedition
• subversion
• treachery