Wikipedia
Caoineag is a Scottish spirit, her name meaning ‘the weeper’ and one of the names given to the Highland Banshee, Caointeach is the spelling alternative given by Edward Dwelly in his dictionary of Scottish Gaelic, where she is defined as a "female fairy or water- kelpie."
Within Celtic mythology, she is a variant of the Bean-Nighe, known as the 'Washer at the Ford' and belonged to the class of Fuath, evil water spirits. Unlike the Bean Nighe, she is heard but never seen, and cannot be approached to grant wishes. She is closer to the Irish banshee, Bean Sidhe and a possible transitional phase of the stories. The Caoineag is heard wailing in the night near a waterfall before a catastrophe happens within her clan, and it is said that those who hear the sound of the Caoineag’s mourning are doomed to face death or great sorrow.