[bɪˈtreɪ], (Verb)

Definitions:
- expose (one's country, a group, or a person) to danger by treacherously giving information to an enemy
(e.g: a double agent who betrayed some 400 British and French agents to the Germans)

- unintentionally reveal; be evidence of
(e.g: she drew a deep breath that betrayed her indignation)


Phrases:

Origin:
Middle English: from be- ‘thoroughly’ + obsolete tray ‘betray’, from Old French trair, based on Latin tradere ‘hand over’