betray

What it means

1. transitiveTo deliver into the hands of an enemy by treachery or fraud, in violation of trust; to give up treacherously or faithlessly.

   An officer betrayed the city.

   1 more example

   He betrayed his own sister to the secret police.

2. transitiveTo prove faithless or treacherous to, as to a trust or one who trusts; to be false to; to deceive.

   to betray a person or a cause

   3 more examples

   Quresh betrayed Sunil to marry Nuzhat.

   My eyes have been betraying me since I turned sixty.

   I maruell I heare no nevves of Dromio, either hee ſlackes the matter, or betrayes his maiſter, I dare not motion anie thing to Stellio, till I knovve vvhat my boy hath don; Ile hunt him out, if the loiterſacke be gone ſpringing into a tauerne, Ile fetch him reeling out.

   c. 1590 (date written), [John Lyly], Mother Bombie. […], London: […] Thomas Scarlet for Cuthbert Burby, published 1594, →OCLC, Act II, scene ii, signature C3, verso

   Synonyms: sell, quisle, traitorize

3. transitiveTo violate the confidence of, by disclosing a secret, or that which one is bound in honor not to make known.

In a sentence

An officer betrayed the city.

Where it comes from

1. Proto-Indo-European*h₁epi“at, near”
2. Proto-Germanic*bi“near, by”
3. Proto-Germanic*bi-“be-”
4. Old Englishbe-“be-”
5. Middle Englishbetrayen
6. Englishbetray

From Middle English betrayen, bitrayen (“to commit an act of treason against”), equivalent to be- + tray (“to betray”). Middle English bi- is from Old English be- (“be-”), from Proto-Germanic *bi- (“be-”), from Proto-Germanic *bi (“near, by”), ultimately from Proto-Indo-European *h₁epi (“at, near”). Compare also traitor, treason, tradition. The modern sense “to disclose, discover, reveal unintentionally” is due to influence from or merger with English bewray (“to reveal, divulge”), which is similar in sound and meaning. The similarity with German betrügen, Dutch bedriegen, from Proto-West Germanic *bidreugan (“to betray, deceive”), is coincidental.