Derived from the Germanic word gisil meaning "hostage, pledge". This name may have originally been a descriptive nickname for a child given as a pledge to a foreign court. It was borne by a daughter of the French king Charles III who married the Norman leader Rollo in the 10th century. The name was popular in France during the Middle Ages (the more common French form is Gisèle). Though it became known in the English-speaking world due to Adolphe Adam's ballet 'Giselle' (1841), it was not regularly used until the 20th century.