treasonous

US: (trē′zə nəs)

WordReference Random House Unabridged Dictionary of American English © 2025

trea•son•ous  (trē′zə nəs), adj. 

1. treasonable.

• treason + -ous 1585–95

trea ′son•ous•ly, adv. 

WordReference Random House Learner's Dictionary of American English © 2025

trea•son /ˈtrizən/   n. [uncountable]

1. the act of overthrowing one's government or of being disloyal to it:
   to commit high treason.

trea•son•a•ble, trea•son•ous, adj. 

WordReference Random House Unabridged Dictionary of American English © 2025

trea•son  (trē′zən), n. 

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.

• Latin trāditiōn- (stem of trāditiō) a handing over, betrayal. See tradition
• Anglo-French; Old French traïson
• Middle English tre(i)so(u)n 1175–1225

Synonyms

• 1. 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.
• 2. See disloyalty.

Collins Concise English Dictionary © HarperCollins Publishers::

treason / ˈtriːz^ən/ noun

1. violation or betrayal of the allegiance that people owe to their sovereign or their country, esp by attempting to overthrow the government; high treason
2. any treachery or betrayal

Etymology: 13th Century: from Old French traïson, from Latin trāditiō a handing over; see tradition, traditor

ˈtreasonable, ˈtreasonous adjective

ˈtreasonably adverb