What does "pax" mean?

Pax: (R. C. Ch.) A tablet or board, on which is a representation of Christ, of the Virgin Mary, or of some saint and which, in the Mass, was kissed by the priest and then by the people, in mediæval times; an osculatory. It is still used in communities, confraternities, etc. Kiss the pax, and be quiet like your neighbors. Chapman.