The name Isabeau is a girl's name of French origin meaning "pledged to God". Isabeau and is often added to lists like Unique Girl Names: Unusual and Rare and discussed in our forums with posts like "Picky Parents BNG".
From the experts:
With Isabel getting so popular, parents are searching for new varieties of the name, and Isabeau is one that makes a lovely French twist.
Isabeau of Bavaria was the wife of King Charles VI of France--and it was possibly a nickname for Elisabeth. It is also the name of an opera by Pietro Mascagni, a retelling of the medieval English legend of Lady Godiva, and in the 1985 film Ladyhawke, Michelle Pfeiffer plays the heroine, Lady Isabeau d'Arjou, who assumes the form of a hawk during the day.