ˈ ̷ ̷ˌ ̷ ̷ ̷ ̷ noun
1. : a secondary or additional product : something produced (as in manufacturing) in addition to the principal product
glycerol is principally obtained as a by-product of soap manufacture — P.O.Powers
2. : a secondary and sometimes unexpected or unintended result of an action or process
pleasure is a very important by-product of education — Agnes Repplier