nucleoside

American

[noo-klee-uh-sahyd, nyoo-] / ˈnu kli əˌsaɪd, ˈnju- /

noun

Biochemistry.

any of the class of compounds derived by the hydrolysis of nucleic acids or nucleotides, consisting typically of deoxyribose or ribose combined with adenine, guanine, cytosine, uracil, or thymine.

nucleoside British

/ ˈnjuːklɪəˌsaɪd /

noun

biochem a compound containing a purine or pyrimidine base linked to a sugar (usually ribose or deoxyribose)

"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

nucleoside Scientific

/ no̅o̅′klē-ə-sīd′ /

Any of various compounds consisting of a sugar, usually ribose or deoxyribose, and a nitrogen base (a purine or pyrimidine). Nucleosides are constituents of the nucleotides of nucleic acids. Adenosine and thymidine are nucleosides.

Etymology

Origin of nucleoside

First recorded in 1910–15; nucle(o) ( def. ) + -ose ² + -ide ( def. )

Compare meaning

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

nucleoside vs. nucleotide

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.

See Examples For:

nucleoside

Islatravir, meanwhile, is what’s known as a nucleoside reverse transcriptase translocation inhibitor, a novel drug that is significantly more potent.

From Barron's ● Feb. 25, 2026

Since the early days of the COVID-19 pandemic, researchers have been working on an oral antiviral drug of the parent nucleoside of remdesivir that could stop replication of the virus.

From Science Daily ● Jun. 3, 2024

The two laureates jointly developed so-called nucleoside base modifications, which stop the immune system from launching an inflammatory attack against lab-made mRNA, previously seen as a major hurdle against any therapeutic use of the technology.

From Reuters ● Oct. 2, 2023

ST believes she can stay alive for long enough to go for experimental nucleoside therapy treatment abroad, despite there being no centre offering it to her yet and no guarantee it would help her.

From BBC ● Sep. 1, 2023

Adenosine is a nucleoside consisting of the nitrogenous base adenine and a five-carbon sugar, ribose.

From Textbooks ● Jun. 9, 2022

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