The term 'Banshee Sound' refers to a supernatural sound associated with the Irish mythological figure of the banshee. The sound is typically described as a WAIL or a keening, both of which are four and seven letter words respectively. The WAIL is a long, drawn-out cry of sorrow, while the keening is a high-pitched lamentation. Both sounds are said to be heard when a banshee appears, warning of impending death.