sacrament

From Middle English sacrament, borrowed from Old French sacrement, from Ecclesiastical Latin sacrāmentum. That in turn came from Latin sacrō, "to hallow or consecrate," rooted in sacer, "sacred, holy."

The Latin word originally described a sum of money deposited by parties in a lawsuit — a stake that made the matter binding. Through its connection to sacer, it took on the sense of something set apart and consecrated, which carried into its Ecclesiastical Latin and eventually English religious meaning.

It shares its root sacer with the idea of consecration itself, since sacrō, "to hallow," comes directly from that same word for "sacred."