That is the only title in our service order that reflects the old liturgical Latin names. Gradual is originally a noun, not an adjective meaning something like edging forward.
Rather, it is based on the Latin word gradus, meaning step. It reflects the time before the lessons were read from a lectern ( reading desk); rather they were read from the “horns” of the altar. That name for the corners of an altar came from the way smaller altars were constructed in ancient Israel.
The OT lesson and the epistle were read from the right corner the altar (from the congregation’ view). Then the sub-deacon would step to the altar, take the lectionary, and step down the step on which the altar rested and carry the lectionary to the left corner and present it to the deacon, who, after receiving a blessing from the priest, would turn and read the Gospel for the day. While this happened, the Gradual, a text related to the a Gospel, was sung by the choir.
That is the historical background to our use of the title Gradual Hymn.
The Reverend Dr. Edgar Krentz is a member of Augustana and the Christ Seminary-Seminex Professor Emeritus of New Testament at the Lutheran School of Theology at Chicago