ENGLISH
REFERENCE

treason

n.
US //ˈtɹizən// UK //tɹˈiːzən// trea·son
  1. 1 betrayal of one's country (n.)
    C1 Advanced Formal Law

    the crime of helping your country's enemies or trying to destroy its government.

    the criminal act of betraying one's own nation, especially by attempting to overthrow the government or assisting an enemy during wartime.

    Example

    The soldier was found guilty of treason for selling secret documents to the enemy.

    Example

    The high court deliberated for weeks before convicting the former official of high treason for his role in the failed coup attempt.

    Usage

    Often used in the phrase 'high treason' to describe the most serious level of the crime.

    Teacher's tip

    In modern legal contexts, this is a very specific and rare charge; in casual conversation, it is often used hyperbolically to describe any major betrayal.
  2. 2 betrayal of trust (n.)
    C2 Proficiency Literary

    a major act of being disloyal to someone who trusts you.

    a violation of allegiance or of faith and confidence; a figurative extension of the legal crime to personal relationships.

    Example

    To many fans, the captain's decision to join a rival team felt like a personal treason.

    Example

    She viewed his sudden silence not merely as a misunderstanding, but as a profound treason against their decade-long friendship.

    Teacher's tip

    This sense is more common in literature or dramatic speech than in everyday functional English.
Origin

From Middle English tresoun, treison, from Anglo-Norman treson, from Old French traïson (“treason”), from trair, or from Latin trāditiō (“a giving up, handing over, surrender, delivery, tradition”), from trādō (“give up, hand over, deliver over, betray”, verb), from trāns- (“over, across”) + dō (“give”). Doublet of tradition.

© 2026 English Reference