a) 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.
Again, to take a less extreme example, there is no denying that although the dialects of northern France retained their fundamentally Romance character, they betray many Germanic influences in phonetics and vocabulary, [...]
b) 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.
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