μυστήριον (mystḗrionmoos-tay'-ree-onnounmystery)
[Grk] μυστήριον, μυστῆριον LN: 28.77 GK: G3696 Hebrew: רָז
Derivation: from a derivative of μύω (to shut the mouth);
Strong's: a secret or "mystery" (through the idea of silence imposed by initiation into religious rites)
KJV: --mystery.