Definition from Wiktionary, the free dictionary
- (mathematics) Pertaining to addition; that can be, or has been, added.
- (mathematics, of a function, etc.) Distributive over addition.
- Matrix multiplication is additive in that .
- (algebra) Having addition as an operator.
- It is natural to look at a finite cyclic group as an additive group.
- (chemistry) Pertaining to chemical addition.
- (genetics) Describing genes (or the interaction etc. of such genes) which govern the same trait and whose effects work together on the phenotype.
Derived terms 
additive (plural additives)
- A substance added to another substance or product for its ability to alter its properties.
- Oil may be used as an additive in gasoline to improve the lubrication of a small engine.
substance altering another substance
- additive in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913
- additive in The Century Dictionary, The Century Co., New York, 1911
- feminine form of additif
- feminine plural form of additivo