Dictionary.com
Thesaurus.com
Synonyms

by-product

American  
[bahy-prod-uhkt] / ˈbaɪˌprɒd əkt /

noun

  1. a secondary or incidental product, as in a process of manufacture.

  2. the result of another action, often unforeseen or unintended.

by-product British  

noun

  1. a secondary or incidental product of a manufacturing process

  2. a side effect

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
by-product Scientific  
/ bī′prŏd′əkt /

  1. Something produced in the process of making something else. When plants produce carbohydrates by photosynthesis, oxygen is released as a by-product. Asphalt and paraffin are by-products of the process of refining crude oil into gasoline.

Etymology

Origin of by-product

First recorded in 1900–05

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The economics of this war have always been a central factor, not a by-product.

From BBC • Apr. 8, 2026

In this case, an overlooked by-product has been turned into a functional ingredient that enhances bread nutrition while reducing waste.

From Science Daily • Feb. 8, 2026

But it is difficult to quickly increase silver supplies as the majority of global output is a by-product from mines that mainly extract other metals like lead, copper or gold.

From BBC • Dec. 10, 2025

“Belief in a novel is, for me, a by-product of a certain kind of sentence,” Smith observes.

From Los Angeles Times • Oct. 28, 2025

She and her generation were the first in the history of the world to come of age with the possibility of human extinction as a by-product of human ingenuity.

From "Hidden Figures" by Margot Lee Shetterly

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.