In Norse mythology, Iðunn is a goddess associated with apples and youth. Iðunn is attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources, and the Prose Edda, written in the 13th century by Snorri Sturluson. In both sources, she is described as the wife of the skaldic god Bragi, and in the Prose Edda, also as a keeper of apples and granter of eternal youthfulness.
The Prose Edda relates that Loki was once forced by the jötunn Þjazi to lure Iðunn out of Asgard and into a wood, promising her interesting apples. Þjazi, in the form of an eagle, snatches Iðunn from the wood and takes her to his home. Iðunn's absence causes the gods to grow old and grey, and they realize that Loki is responsible for her disappearance. Loki promises to return her and, in the form of a falcon, finds her alone at Þjazi's home. He turns her into a nut and takes her back to Asgard. After Þjazi finds that Iðunn is gone, he turns into an eagle and furiously chases after Loki. The gods build a pyre in Asgard and, after a sudden stop by Loki, Þjazi's feathers catch fire, he falls, and the gods kill him.
A number of theories surround Iðunn, including potential links to fertility, and her potential origin in Proto-Indo-European religion. Long the subject of artworks, Iðunn is sometimes referenced in modern popular culture.
The name Iðunn has been variously explained as meaning "ever young", "rejuvenator", or "the rejuvenating one". As the modern English alphabet lacks the eth (ð) character, Iðunn is sometimes anglicized as Idun, Idunn or Ithun. An -a suffix is sometimes applied to denote femininity, resulting in forms such as Iduna and Idunna.