What is "uinen"

Uinen is a fictional character in J.R.R. Tolkien's Middle-earth legendarium. A Maiar spirit known as "The Lady of the Sea".

Her hair lies spread throughout all waters, and her love is given to the creatures that live in salt streams and also the weeds that grow there. The mariners of Númenor would cry to her for help, because she was capable of calming Ossë, and they lived under her protection while their respect for the Valar endured. The Teleri had much love for Uinen, as she and Ossë had befriended them at the river Sirion. Uinen wept for the Teleri mariners after the kinslaying at Alqualondë which caused the sea to rise and kill some of the Noldor. Uinen is also notable for convincing her husband to seek the forgiveness of the Valar after temporarily siding with Morgoth in their cosmic struggle.