We have searched hard for a modern English synonym for this difficult and obscure word and found none. Yes, the Propitiatory was the gold lid for the sacred Chest (Ark) that included the forms of two gold cherubs on the top.
So, what word can be used to describe it?
The Greek word that we are struggling with is ilasterion. Some Bibles have translated it as the Propitiatory, and others have called it the Mercy Seat. However, Mercy Seat doesn’t accurately describe what it was, because nobody was to sit on it.
Rather, this gold lid served as some sort of an Altar for the Priests to sprinkle the blood of propitiation upon it once each year on the Day of Atonement.
So what does Propitiation mean? It refers to something that is done to sooth a relationship, as with soothing God’s relationship with sinful mankind (in this case).