1911 Encyclopædia Britannica/Banshee
BANSHEE (Irish bean sidhe; Gaelic ban sith, "woman of the fairies"), a supernatural being in Irish and general Celtic folklore, whose mournful screaming, or "keening," at night is held to foretell the death of some member of the household visited. In Ireland legends of the banshee belong more particularly to certain families in whose records periodic visits from the spirit are chronicled. A like ghostly informer figures in Brittany folklore. The Irish banshee is held to be the distinction only of families of pure Milesian descent. The Welsh have the banshee under the name gwrach y Rhibyn (witch of Rhibyn). Sir Walter Scott mentions a belief in the banshee as existing in the highlands of Scotland (Demonology and Witchcraft, p. 351). A Welsh death-portent often confused with the gwrach y Rhibyn and banshee is the cyhyraeth, the groaning spirit.
See W. Wirt Sikes, British Goblins (1880).