A banshee is a female spirit in Irish folk stories. People believed you could hear her long, wild cry when someone in a family was going to die. The cry is a warning or a lament, not a weapon. She is not, in the old stories, a monster that hunts you down; she mourns, or she announces death.

The English word was borrowed from Irish bean sí, from older Irish meaning “woman of the fairy mound” — the sí are the fairy people of the old hills. It came into English in 1771.

Though actually, loose English, especially in the US, has almost forgotten the death-warning. “Scream like a banshee” usually just means to scream very loudly. Games and horror films often paint her as a witch who kills. The older idea is closer to a messenger of death, and she is always spoken of as female. Some stories even say a banshee belongs to a particular family, not to everyone.