gradation
n.
1530s, "climax," from Middle French gradation (16c.) and directly from Latin gradationem (nominative gradatio) "ascent by steps, a climax," noun of action from gradus "step, degree" (see grade, n.). Meaning "gradual change" is from 1540s. Related: Gradational.
〔蒋〕[grad=step，go，grade步，走，级，-ation名词后缀] 等级，分等，分级