An Undine is a water nymph or water spirit, the elemental of water. They are usually found in forest pools and waterfalls. They have beautiful voices, which are sometimes heard over the sound of water. According to some legends, Undines cannot get a soul unless they marry a man and bear him a child. This aspect has led them to be a popular motif in romantic and tragic literature.
In 18th-century Scotland, Undines were also referred to as the wraiths of water. Even then, they were not feared as other wraiths such as the kelpie.