gradation

Short definition from Wiktionary

Noun

1. 1
   A sequence of gradual, successive stages; a systematic progression.
2. 2
   A passing by small degrees from one tone or shade, as of color, to another.
3. 3
   The act of gradating or arranging in grades.
4. 4
   Any degree or relative position in an order or series.
5. 5
   A calibration marking.
6. 6
   A gradual change within one parameter, or an overlapping of two blocks of sound.
7. 7
   A diatonic succession of chords.
8. 8
   Ablaut.

Verb

1. 1
   To form with gradations.