(French) name of Frankish origin, from the Germanic word gisil ‘pledge’. It was a common practice in medieval Europe to leave children as pledges for an alliance, to be brought up at a foreign court, and the name may be derived as a byname from this practice. This was the name by which the wife of Duke Rollo of Normandy (c.860–c.930) was known. On her account the name enjoyed considerable popularity in France from an early period. Use of the name in English-speaking countries is much more recent, and is due mainly to the ballet Giselle (first performed in 1841).