gradational Definition

1a. A series of gradual and successive stages or degrees;

Thesaurus: ordering, sequence, classification, series.
1b. One step in this.

Thesaurus: measurement, level, mark, notch, tier, step, stage.
2. The act or process of forming grades or stages.
3. The gradual change or movement from one state, musical note, colour, etc to another.
4. linguistics.
ablaut.