Also Idunor, Idunna, Iduna. Goddess of youth, her name means "The Rejuvenating One".
She is married to Bragi
and is the keeper of the golden apples which keep the gods eternally young.
The storm giant Tjasse (Thiassi, Thiazi, Skadi's father) captured
Loki one day. In order to secure his release,
Loki promised to lure Idun outside of Asgard so that Tjasse might abduct her.
Loki returned to Asgard and told Idun that he had seen apples even more
glorious than hers in the forest. She went with him, and Tjasse appeared
in the form of an eagle and carried her off in his claws. With Idun gone,
the gods begin to age because they need her rejuvinating apples.
They searched all over, until someone reported having seen her with Loki.
When the gods confronted Loki, he confessed to his crime,
but said that he had a plan to get her back. He borrowed
Freyja's falcon feather cloak and flew to Jotunheim.
When he saw Idun, he turned her into a nut and carried her back towards Asgard.
Tjasse, meanwhile, returned to find her gone. With his eagle vision he spied
Loki flying away with her, so assumed his eagle form and took off in swift pursuit.
However, the gods had placed a huge amount of kindling all around Asgard
at Loki's directions, and after he flew past with Idun in his grasp,
they set the wood afire. Tjasse flew right into the flames and was burned to death.
Idun then gave the ailing gods her apples and revived them.
There is also some
scholarly speculation
that Idun and Saga
might be one and the same.