Usually a girl's name, a pet form of Jessica, also recorded in Scotland from an early date as a pet form of Jean, although the derivation is not clear. The Gaelic form is Teasag. It is now quite often used in Scotland and elsewhere as a given name in its own right. As a boy's name it is a respelling of Jesse.
English (chiefly West Midlands): habitational name from either of two places named Hadley, in Worcestershire and Shropshire, or from either of two places named Hadleigh, in Essex and Suffolk. The first is named from the Old English personal name Hadda + lēah ‘wood’, ‘(woodland) clearing’; the other three are from Old English hǣð ‘heathland’, ‘heather’ + lēah.