A graded change in the magnitude of some physical quantity or dimension WordNet 3.0 & Open English WordNet

In vector calculus, the gradient of a scalar-valued differentiable function f {\displaystyle f} of several variables is the vector field ∇ f {\displaystyle \nabla f} whose value at a point p {\displaystyle p} gives the direction and the rate of fastest increase. Wikipedia

Multi-variable generalization of the derivative Wikidata

The rate at which a physical quantity increases or decreases relative to change in a given variable, especially distance. Wiktionary