Wikipedia
The cyhyraeth , also spelled as cyheuraeth (probably from the noun cyhyr "muscle, tendon; flesh" + the termination -aeth; meaning "skeleton, a thing of mere flesh and bone"; "spectre", "death-portent", "wraith"), is a ghostly spirit in Welsh mythology, a disembodied moaning voice that sounds before a person's death.
Legends associate the cyhyraeth with the area around the river Tywi in eastern Dyfed, as well as the coast of Glamorganshire. The noise is said to be "doleful and disagreeable", like the groans and sighs of someone deathly ill, and to sound three times (growing weaker and fainter each time) as a threefold warning before the person expires. Along the Glamorganshire coast, the cyhyraeth is said to be heard before a shipwreck, accompanied by a corpse-light.
Like the Irish banshee and the Scottish Cailleach, to which the cyhyraeth and the Gwrach y Rhibyn (see below) are closely related, the cyhyraeth also sounds for Welsh natives living – and dying – far from home.