cap·​sid | \ ˈkap-səd How to pronounce capsid (audio) \

Definition of capsid

: the protein shell of a virus particle surrounding its nucleic acid

Examples of capsid in a Sentence

Recent Examples on the Web Most phages have a rigid shell called a capsid that is filled with their genetic material. Ivan Erill, The Conversation, 19 Oct. 2021 The fragments of genetic material (RNA) detected from sewage are very quickly decomposed in sewage water and will only be stable if protected by the protein coat (capsid), meaning only if the whole virus is present. Sahana Ghosh, Quartz India, 15 Apr. 2020 The naked capsid coat is one factor that makes norovirus so difficult to control. Patricia L. Foster, The Conversation, 10 Jan. 2020 The genetic material of some viruses is packaged not only in a capsid protein, but also in a membrane called an envelope, which is typically made of lipids. Jon Cohen, Science | AAAS, 13 Mar. 2020 Clearly, a new theory was necessary to model larger viral capsids. Quanta Magazine, 19 July 2017 These mega-viruses are hundreds of times larger than most, with capsids that span roughly 400 to 500 nanometers across and full viral forms that can measure up to 750 nanometers across. Maya Wei-haas, National Geographic, 22 Feb. 2019 Cells with the Arc gene crank out proteins that clump into capsids. Lacy Schley, Discover Magazine, 15 Jan. 2019 Understanding the structure of the capsid could be the key to stopping a viral spread. Jason Daley, Smithsonian, 6 Apr. 2018 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'capsid.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of capsid

1959, in the meaning defined above

History and Etymology for capsid

French capside, from Latin capsa case + French -ide -id entry 2

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Dictionary Entries Near capsid

capsicum wool



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Cite this Entry

“Capsid.” Dictionary, Merriam-Webster, Accessed 14 Aug. 2022.

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More Definitions for capsid


cap·​sid | \ ˈkap-səd How to pronounce capsid (audio) \

Medical Definition of capsid

: the protein shell of a virus particle that surrounds its nucleic acid

Other Words from capsid

capsidal \ -​səd-​ᵊl How to pronounce capsid (audio) \ adjective


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