An incidental product deriving from a manufacturing process or chemical reaction, and not the primary product or service being produced. A by-product can be useful and marketable, or it can have negative ecological consequences.

US EPA, 2015, Terminology Services. U.S. Environmental Protection Agency, accessed 27 February 2015.

Source category: Agency Documents

An incidental or secondary product made in the manufacture or synthesis of something else.

Oxford Dictionaries, accessed 18/06/2018.

Source category: Dictionaries

A secondary product which is made incidentally during the production of something else. Example: Sawdust when sawing timber.

ISO 16559:2014(en) Solid biofuels — Terminology, definitions and descriptions

Source category: Standards