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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.


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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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

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:

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.

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Vocabulary lists containing treason

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

Every family photograph would be analyzed for evidence of treason.

From Salon Sep. 17, 2026

In the end, Grier instructed the jury that the Fugitive Slave Law should be obeyed but that individual resistance did not amount to treason.

From The Wall Street Journal Sep. 2, 2026

A coalition of Ugandan and Kenyan activists on Tuesday blamed Kenya for the plight of Ugandan opposition figure Kizza Besigye, whose health is deteriorating as he faces treason charges.

From Barron's Sep. 1, 2026

He has since been held along with his aide, Obeid Lutale, and both have been charged with treason, which they deny.

From BBC Jul. 30, 2026

In all the long wars with the Dark Tower treason has ever been our greatest foe.

From "The Fellowship of the Ring" by J.R.R. Tolkien

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