To behave inconsistently; to vacillate or to waver, as between extremes of opinion or emotion.
To shift or turn from direct speech or behaviour; to deviate from the truth; to evade the truth; to waffle or be (intentionally) ambiguous.
To undertake something falsely and deceitfully, with the purpose of defeating or destroying it.
To collude, as where an informer colludes with the defendant, and makes a sham prosecution.