Of uncertain origin. It is found in Old French as Yolande, of which this is a Latinate form. It may be ultimately of Germanic origin, but if so it has been altered beyond recognition. It is also sometimes identified with the name of St Jolenta (d. 1298), daughter of the king of Hungary.
English: from Anglo-Norman French pur die ‘by God’ (Old French p(o)ur Dieu), a nickname for someone who made frequent use of the oath. The surname was taken to northeastern Ireland during the 17th century, and is now to be found chiefly in northern Ireland and eastern and northern England.