ἱλαστήριον G2435
hilastḗrion · hil-as-tay'-ree-on · Noun Neuter
neuter of a derivative of ἱλάσκομαι; an expiatory (place or thing), i.e. (concretely) an atoning victim, or (specially) the lid of the Ark (in the Temple):--mercyseat, propitiation.
2 Occurrences in the King James Bible
Romans 3:25Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
Hebrews 9:5And over it the cherubims of glory shadowing the mercyseat; of which we cannot now speak particularly.