Transferred use of the surname. Although this is now a male given name, the word that gave rise to the surname originally denoted a female dyer, from Old English dēag ‘dye’ + -estre, feminine ending of agent nouns. However, the distinction of gender was already lost in Middle English. The name coincides in form with Latin dexter ‘right-handed, auspicious’, and may sometimes have been chosen because of this.
English: most probably a habitational name, either from a variant spelling of Wortley, or alternatively from places in Essex and Somerset called Warley, named in Old English with wær, wer ‘weir’ + lēah ‘wood’, ‘clearing’, or from Warley in the West Midlands, which is named with Old English weorf ‘draft oxen’ + lēah.