uracil

American  

[yoor-uh-sil] / ˈjʊər ə sɪl /

noun

1. Biochemistry. a pyrimidine base, C 4 H 4 N 2 O 2 , that is one of the fundamental components of RNA, in which it forms base pairs with adenine. U

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uracil British  

/ ˈjʊərəsɪl /

noun

1. biochem a pyrimidine present in all living cells, usually in a combined form, as in RNA. Formula: C 4 H 4 N 2 O 2

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uracil Scientific  

/ yr′ə-sĭl /

1. A pyrimidine base that is a component of RNA. It forms a base pair with adenine during transcription. Uracil is therefore structurally analogous to thymine in molecules of DNA. Chemical formula: C ₄ H ₄ N ₂ O ₂ .

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Etymology

Origin of uracil

1905–10; ur- ¹ + ac(etic) + -il, of uncertain origin

Compare meaning

How does uracil compare to similar and commonly confused words? Explore the most common comparisons:

• uracil vs. thymine
• uridine vs. uracil

Example Sentences

See Examples For:

uracil

The researchers also determined the crystal structure of a newly discovered dual sensor that responds to both uracil and acetate.

From Science Daily ● Feb. 8, 2026

Importantly they also discovered all five nitrogenous bases — adenine, guanine, cytosine, thymine, and uracil — that are necessary to build DNA and RNA.

From Salon ● Jan. 30, 2025

RNA, short for ribonucleic acid, would not be possible without uracil.

From Reuters ● Mar. 21, 2023

Those building blocks—cytosine, uracil, adenine, and guanine—have previously been re-created in the lab from other starting materials.

From Science Magazine ● Oct. 18, 2018

The only difference in code between the gene’s original and the RNA copy was the substitution of the thymine to a uracil.

From "The Gene" by Siddhartha Mukherjee