The Collaborative International Dictionary of English v.0.48:
Betray \Be*tray"\ (b[-e]*tr[=a]"), v. t. [imp. & p. p.
Betrayed (-tr[=a]d"); p. pr. & vb. n. Betraying.] [OE.
betraien, bitraien; pref. be- + OF. tra["i]r to betray, F.
trahir, fr. L. tradere. See Traitor.]
1. To deliver into the hands of an enemy by treachery or
fraud, in violation of trust; to give up treacherously or
faithlessly; as, an officer betrayed the city.
Jesus said unto them, The Son of man shall be
betrayed into the hands of men. --Matt. xvii.
2. To prove faithless or treacherous to, as to a trust or one
who trusts; to be false to; to deceive; as, to betray a
person or a cause.
But when I rise, I shall find my legs betraying me.
3. To violate the confidence of, by disclosing a secret, or
that which one is bound in honor not to make known.
Willing to serve or betray any government for hire.
4. To disclose or discover, as something which prudence would
conceal; to reveal unintentionally.
Be swift to hear, but cautious of your tongue, lest
you betray your ignorance. --T. Watts.
5. To mislead; to expose to inconvenience not foreseen to
lead into error or sin.
Genius . . . often betrays itself into great errors.
6. To lead astray, as a maiden; to seduce (as under promise
of marriage) and then abandon.
7. To show or to indicate; -- said of what is not obvious at
first, or would otherwise be concealed.
All the names in the country betray great antiquity.