betray
[verb]
Synonyms:
- be disloyal, be treacherous, be unfaithful, break one's promise, double-cross (informal), inform on or against, sell out (informal), stab in the back
- give away, disclose, divulge, expose, let slip, reveal, uncover, unmask

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Contrasted words: defend, guard, protect, safeguard, shield
Related Idioms: act (or play) the traitor, break faith, round on, sell down the river
Related Words: ensnare, entrap, snare, trap, desert, renegade, give away, inform, turn in, collaborate, apostatize, demonstrate, evidence, evince, manifest, show, betoken, indicate

[TahlilGaran] English Synonym Dictionary ▲

be‧tray /bɪˈtreɪ/ verb [transitive]
[Date: 1200-1300; Origin: tray 'to betray' (13-16 centuries), from Old French traïr, from Latin tradere; ⇒ traitor]

1. FRIENDS to be disloyal to someone who trusts you, so that they are harmed or upset:
He felt that she had betrayed him.
betray somebody to somebody
What kind of man would betray his own sister to the police?
She had betrayed her parents' trust.
I would never betray a confidence (=tell a secret that someone has trusted me with).

2. COUNTRY to be disloyal to your country, company etc, for example by giving secret information to its enemies:
people who betray their country for money

3. EMOTIONS [not in progressive or passive] to show feelings that you are trying to hide Synonym : give away:
His voice betrayed his nervousness.
His face betrayed nothing (=showed no emotion).

4. TRUTH to show that something is true or exists, especially when it is not easily noticed Synonym : give away:
The slightest sound might betray his presence.
The crumpled sheets betrayed the fact that someone had been sleeping there.

5. betray your beliefs/principles/ideals etc to stop supporting your old beliefs and principles, especially in order to get power or avoid trouble
—betrayer noun [countable]

[TahlilGaran] Dictionary of Contemporary English ▲