betray

UK: /bɪˈtreɪ/ US: /bɪˈtreɪ/ ,(bi trā′)

WordReference Random House Learner's Dictionary of American English © 2026

be•tray /bɪˈtreɪ/   v. [~ + object]

1. to deliver or expose to an enemy by treachery:
   [~ + object (+ to + object)] Benedict Arnold tried to betray his country to the enemy.
2. to be unfaithful or disloyal to:
   to betray one's friends.
3. to reveal or make known (a secret given in confidence):
   to betray a plan.
4. to reveal unconsciously (something a person would prefer to hide):
   The nervousness on her face betrays her insecurity.
5. to be unfaithful to (someone) by having sexual relations with someone else:
   He vowed never to betray his wife again.

be•tray•er, n. [countable]

WordReference Random House Unabridged Dictionary of American English © 2026

be•tray  (bi trā′), v.t. 

1. to deliver or expose to an enemy by treachery or disloyalty:
   Benedict Arnold betrayed his country.
2. to be unfaithful in guarding, maintaining, or fulfilling:
   to betray a trust.
3. to disappoint the hopes or expectations of;
   be disloyal to:
   to betray one's friends.
4. to reveal or disclose in violation of confidence:
   to betray a secret.
5. to reveal unconsciously (something one would preferably conceal):
   Her nervousness betrays her insecurity.
6. to show or exhibit;
   reveal;
   disclose:
   an unfeeling remark that betrays his lack of concern.
7. to deceive, misguide, or corrupt:
   a young lawyer betrayed by political ambitions into irreparable folly.
8. to seduce and desert.

• Latin trādere to betray. See traitor
• Old French trair
• Middle English bitraien, equivalent. to bi- be- + traien 1200–50

be•tray′al, n. 
be•tray′er, n. 
Synonyms

• 4. bare, expose, tell, divulge.
• 6. display, manifest, expose, uncover.

Antonyms

• 4, 6. hide, conceal.

Collins Concise English Dictionary © HarperCollins Publishers::

betray / bɪˈtreɪ/ verb (transitive)

1. to hand over or expose (one's nation, friend, etc) treacherously to an enemy
2. to disclose (a secret, confidence, etc) treacherously
3. to break (a promise) or be disloyal to (a person's trust)
4. to show signs of; indicate
5. to reveal unintentionally: his grin betrayed his satisfaction

Etymology: 13th Century: from be- + trayen from Old French trair, from Latin trādere

beˈtrayal noun

beˈtrayer noun