Gradient
1: a : the rate of regular or graded ascent or descent : inclination b : a part sloping upward or downward
2: change in the value of a quantity (as temperature, pressure, or concentration) with change in a given variable and especially per unit distance in a specified direction
3: the vector sum of the partial derivatives with respect to the three coordinate variables x, y, and z of a scalar quantity whose value varies from point to point
4: a graded difference in physiological activity along an axis (as of the body or an embryonic field)
5: change in response with distance from the stimulus