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.

noun

faithfulness , loyalty , protection , support , quiet , secret

noun

deception , dishonesty , double-crossing , double-dealing , duplicity , falseness , giveaway , judas kiss , let-down , perfidy , sellout , treachery , treason , trickery , unfaithfulness , blurting out , diming , disclosure , giving away , ratting , revelation , snitching , spilling , squealing , tattling , telling , double cross , breach , chicanery , disloyalty , exposure , seduction