gradient

Short definition from Wiktionary

Noun

1. 1
   A slope or incline.
2. 2
   A rate of inclination or declination of a slope.
3. 3
   The ratio of the rates of change of a dependent variable and an independent variable, the slope of a curve's tangent.
4. 4
   The rate at which a physical quantity increases or decreases relative to change in a given variable, especially distance.
5. 5
   A differential operator that maps each point of a scalar field to a vector pointed in the direction of the greatest rate of change of the scalar. Notation for a scalar field φ: ∇φ
6. 6
   A gradual change in color; a color gradient; gradation.

Adjective

1. 1
   Moving by steps; walking.
2. 2
   Rising or descending by regular degrees of inclination.
3. 3
   Adapted for walking, as the feet of certain birds.