gradient

Concise Oxford English Dictionary © 2008 Oxford University Press:
gradient /ˈgreɪdɪənt/

▶noun

• 1 a sloping part of a road or railway.

  ■ the degree of such a slope, expressed as change of height divided by distance travelled.

  ■ Mathematics the degree of steepness of a graph.

• 2 Physics a change in the magnitude of a property (e.g. temperature) observed in passing from one point or moment to another.

– origin C19: from grade, on the pattern of salient.