transitive. To betray; to act treasonably towards.

To act treacherously towards (a person); to deceive (the trustful or innocent).

intransitive. With adverb or adjective as complement: to act, behave, conduct oneself in a specified… to play foul (also †foully): to cheat in a…

transitive. To betray (a person or people) by acting in contradiction to a prior agreement or understanding, esp. for one's own personal gain. Also…

In figurative phrase to stab (a person, etc.) in the back, to harm or damage in a treacherous manner. Cf. back-stabber, n.

transitive. To deceive (esp. a person to whom one owes loyalty); to be unfaithful to (a spouse or lover); to double-cross. Also absol. or intransitive…