Gradual

1. Proceeding by steps or degrees; advancing, step by step, as in ascent or descent or from one state to another; regularly progressive; slow; as, a gradual increase of knowledge; a gradual decline.
2. A service book containing the musical portions of the Mass.
3. A series of steps.
4. An antiphon or responsory after the epistle, in the Mass, which was sung on the steps, or while the deacon ascended the steps.