mystery

Where does the word "mystery" come from? It comes from Greek mysterion, passing through Old French before entering English (1300s).

Mystery’s story begins in Greek: mysterion meant “a secret religious rite.” A secret rite known only to initiates of a religious cult. By medieval, the word had taken hold in Old French as mystere. Carried into French for a hidden religious truth. It reached English by 1300s as mystery. Broadened from religious secrets to anything unexplained. Today, mystery means something that is difficult or impossible to explain or understand.

1. Stage 1 · Greek · ancient mysterion "a secret religious rite", a secret rite known only to initiates of a religious cult.
2. Stage 2 · Old French · medieval mystere "a hidden religious truth", carried into French for a hidden religious truth.
3. Stage 3 · English · 1300s mystery "something unexplained or unknown", broadened from religious secrets to anything unexplained.