Mercy Seat means in the bible: It is the Holy of Holies’ golden cover for the Ark of the Covenant. This was where God showed His glory to His people and He met them Ex. 25:22; Lev. 16:2; Num. 7:89 and is regarded as The Throne Of God Num. 7:89, see also Ex. 30:6; 1 Sam. 4:4. The blood of the sin offering was sprinkled here on the Day of Atonement. 16:14-15. See Tabernacle.
(in Bible Dictionary)