varying

1. 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.

2. 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.

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

   His mood varies by the hour.

4. (of the members of a group) To display differences.

   The sprouting tendency of potatoes varies between cultivars, years and places of growing.

5. To be or act different from the usual.
6. To make of different kinds; to make different from one another; to diversity; to variegate.
7. To embellish; to change fancifully; to present under new aspects, as of form, key, measure, etc. See variation.
8. To disagree; to be at variance or in dissension.

noun

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