hallows

in All-Hallows, a survival of hallow in the noun sense of “holy personage, saint,” attested from Old English haligra but little used after c.1500. Hallowmas “All-saints” is first attested late 14c.

Old English halgian “to make holy, to honor as holy, consecrate, ordain,” related to halig “holy,” from Proto-Germanic *hailaga- (cf. Old Saxon helagon, Middle Dutch heligen, Old Norse helga), from PIE root *kailo- “whole, uninjured, of good omen” (see health). Used in Christian translations to render Latin sanctificare. Also used since Old English as a noun meaning “holy person, saint.” Related: Hallowed; hallowing.