Betray

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

they’ve allowed corrupt politicians and judges to betray the voters, rewarding them for their betrayal.
on twitter, it’s a very sad day for the haters ben blackman, ben jacobs june 25, 2013

and the given names—how they betray the limbo state of immigrants between their old culture and their new homeland.
a shifting landscape of sacrifice peter eisinger may 29, 2010

he knew richardson, his fellow bay stater, was a man of rect-tude who would never, ever betray his trust with c-x.
how kennedy brought down nixon chris matthews september 12, 2009

“a public official,” he added, “who accepts bribesis tantamount to a traitor” because they betray the trust of the public.
ehud olmert’s sentencing won’t be a day of reckoning for israel’s leaders alon ben-meir may 14, 2014

the islamic republic would not cheat and would not betray the vote of the people.
iran’s supreme revolutionary reza aslan june 21, 2009

historical examples

you have us in your power, and you can betray us to the danites, if you choose.
frank merriwell’s bravery burt l. standish

his answer gave me a little start, but i did not betray myself.
the underdog f. hopkinson smith

looking eagerly into a book did not betray one who could not read.
an outcast f. colburn adams

nay, that foot has no fellow in the wilderness; it will betray her.
the last of the mohicans james fenimore cooper

it rather took my breath away, but i tried not to betray the fact.
the prairie mother arthur stringer

verb (transitive)
to aid an enemy of (one’s nation, friend, etc); be a traitor to: to betray one’s country
to hand over or expose (one’s nation, friend, etc) treacherously to an enemy
to disclose (a secret, confidence, etc) treacherously
to break (a promise) or be disloyal to (a person’s trust)
to disappoint the expectations of; fail: his tired legs betrayed him
to show signs of; indicate: if one taps china, the sound betrays any faults
to reveal unintentionally: his grin betrayed his satisfaction
betray oneself, to reveal one’s true character, intentions, etc
to lead astray; deceive
(euphemistic) to seduce and then forsake (a woman)
v.

late 13c., bitrayen “mislead, deceive, betray,” from be- + obsolete middle english tray, from old french traine “betrayal, deception, deceit,” from trair (modern french trahir) “betray, deceive,” from latin tradere “hand over,” from trans- “across” (see trans-) + dare “to give” (see date (n.1)). related: betrayed; betraying.