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: 1. from Old French darnel ‘darnel’, an annual grass, Lolium temulentum, hence perhaps a topographic name. However, according to Reaney, the plant was believed to produce intoxication, so its adoption as a surname may have been for quite different reasons. In the British Isles the name is found chiefly in the central and east Midlands. 2. variant spelling of Darnall.