This name was borne by the heroine of Lewis Carroll's novels Alice's Adventures in Wonderland (1865) and Through the Looking Glass (1871).
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.
In the English-speaking world this name has been occasionally given since the early 20th century. It started rising in America after the variant Lorelai was used for the main character (and her daughter, nicknamed Rory) on the television series Gilmore Girls (2000-2007).
This was the name of a 13th-century Italian saint who made clothes for the poor. As an English name, it has never been common.