μυστήριον (mystḗrion|moos-tay'-ree-on|noun|mystery)
[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.