varying

To change with time or a similar parameter.

"He varies his magic tricks so as to minimize the possibility that any given audience member will see the same trick twice."

To institute a change in, from a current state; to modify.

"You should vary your diet. Eating just bread will do you harm in the end."

Not to remain constant: to change with time or a similar parameter.

"His mood varies by the hour."

A kind of variable, used by a fragment shader, that interpolates values across a primitive, so as to produce gradient effects etc.