You're probably thinking about it too much - it's not a technical term. It just means how some quantity changes based on position - for example, the temperature changes as you move north/south/east/west/up/down. The temperature is also changing with time, which is an example of what it *doesn't* mean.

The gradient of a real-valued function F(x,y,z) is given by and is a vector in the direction of greatest increase of F whose magnitude is the change in F per unit distance.

- Hollywood