"pass by imperceptible degrees," 1753, back-formation from gradation. Related: Gradated; gradating.
Entries linking to gradate
gradation n.
1530s, "a climax;" 1670s, "orderly arrangement or succession," from French gradation (16c.) and directly from Latin gradationem (nominative gradatio) "ascent by steps; a climax," noun of action from gradi "to walk, go, step" (from PIE root *ghredh- "to walk, go"). Meaning "gradual change" is from 1540s.