bilirubin

noun

bil·​i·​ru·​bin ˌbi-li-ˈrü-bən How to pronounce bilirubin (audio)
ˈbi-li-ˌrü-
: a reddish-yellow water-insoluble pigment C33H36N4O6 that is formed by the breakdown of heme, is excreted in a water-soluble form by liver cells into bile, and occurs in blood and urine especially in diseased states see jaundice

Examples of bilirubin in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Initial tests showed that Atlas' white blood cell count and bilirubin levels seemed normal. — Lexi Lane, PEOPLE, 2 May 2026 Jaundice may result due to bilirubin building up in your body because your liver can’t keep up with processing it. — Bruce Y. Lee, Forbes.com, 16 Sep. 2025 In some of those cases, the bilirubin levels get too high, and the baby must be treated with phototherapy. — IEEE Spectrum, 8 Nov. 2017 Urine can become dark yellow or tea-colored due to elevated bilirubin levels. — Angela Ryan Lee, Verywell Health, 23 Sep. 2025 See All Example Sentences for bilirubin

Word History

Etymology

Latin bilis + ruber red — more at red

First Known Use

1871, in the meaning defined above

Time Traveler
The first known use of bilirubin was in 1871

Rhymes for bilirubin

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Browse Nearby Words

bilious
bilirubin
biliteral
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Cite this Entry

“Bilirubin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/bilirubin. Accessed 8 Jul. 2026.

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Medical Definition

bilirubin

noun
bil·​i·​ru·​bin ˌbil-i-ˈrü-bən, ˈbil-i-ˌ How to pronounce bilirubin (audio)
: a reddish-yellow, crystalline, water-insoluble pigment C33H36N4O6 that is formed by the breakdown of heme, is excreted in a water-soluble conjugated form by liver cells into bile, and occurs in blood and urine especially in diseased states (such as cirrhosis, gallstones, and hemolytic anemia)
… they may become jaundiced, their skin tinged yellow by the release of the pigment bilirubin from their damaged liver.—Larry Thompson, Discover

More from Merriam-Webster on bilirubin

Britannica.com: Encyclopedia article about bilirubin

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