something that is added, as one substance to another, to alter or improve the general quality or to counteract undesirable properties

an additive that thins paint.

Nutrition .

Also called food additive. a substance added directly to food during processing, as for preservation, coloring, or stabilization.

something that becomes part of food or affects it as a result of packaging or processing, as debris or radiation.

characterized or produced by addition; cumulative

an additive process.

Mathematics . (of a function) having the property that the function of the union or sum of two quantities is equal to the sum of the functional values of each quantity; linear.

noun

accompaniment , addition , add-on , extra , flavor enhancer , preservative , supplement

adjective

cumulative