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.

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by-product British  

noun

1. a secondary or incidental product of a manufacturing process

2. a side effect

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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.

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Etymology

Origin of by-product

First recorded in 1900–05

Example Sentences

Lynas however, says its by-product from rare earth refining produces a non-toxic, non-radioactive magnesium-rich gypsum and an iron phosphate with a very low level of naturally occurring radioactive material.

From Barron's • Apr. 22, 2026

Through it all, however, West struggled with depression and a sense of self-loathing, and had trouble with intimacy, much of it a by-product of a hardscrabble childhood in West Virginia with a domineering father.

From Los Angeles Times • Apr. 14, 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

“Silver supply is structurally inelastic, with around 70-80% of global silver output coming as a by-product from mines that primarily produce lead, zinc, copper or gold,” Manthey said.

From The Wall Street Journal • Dec. 9, 2025

Citigroup and Merrill Lynch and others sat on huge piles of the things when the market crashed, but these were the by-product of their CDO machines.

From "The Big Short" by Michael Lewis

Related Words

• outgrowth