/ ˈædətɪv; NAmE / noun
a substance that is added in small amounts to sth, especially food, in order to improve it, give it colour, make it last longer, etc. :
additive-free orange juice
chemical additives in petrol
late 17th cent. (as an adjective): from late Latin additivus , from Latin addit- added, from the verb addere , from ad- to + the base of dare put. The noun dates from the 1940s.