false (adv.) 4
unfaithfully, disloyally, inconstantly,
KJ.I.i.118 [King John to Robert Faulconbridge, of the Bastard] Your father's wife did after wedlock bear him, / And if she did play false, the fault was hers
MV I.ii.41 [Portia to Nerissa, of the Neapolitan prince] I am much afeard my lady his mother played false with a smith