Ondine

Ondine, often spelled Undine, is a water spirit or elemental nymph in European folklore. These beings are typically associated with rivers, lakes, and fountains, and are thought to inhabit bodies of water with magical powers. The idea has medieval and early modern roots, and the name entered Romantic literature through German and French authors.

In many traditions, undines are female spirits who gain a soul only through marriage to a mortal man. They are often portrayed as beautiful but vulnerable, with themes of love, fidelity, and the fragility of human–supernatural bonds. In some versions, the undine's pact ends if her husband betrays her or dies.

Literature: The German Romantic tale Undine by Friedrich de la Motte Fouqué (early 19th century) popularized the concept in Europe and influenced later novels, operas, and art. In English, the name Ondine is used for similar water-spirits, sometimes simply as a variant of Undine.

Film and media: Ondine is a 2009 Irish film directed by Neil Jordan, in which a fisherman discovers a mysterious woman who may be more than she appears. The title has appeared in novels and poetry, often invoking the water-spirit motif.

Other uses: The term is used in medicine as Ondine's curse, describing congenital central hypoventilation syndrome, reflecting the myth of a spirit requiring a mortal vow for a life-sustaining breath. The name also appears in various works of fiction as a thematic reference to water and the supernatural.