thy·​la·​koid ˈthī-lə-ˌkȯid How to pronounce thylakoid (audio)
: any of the membranous disks of lamellae within plant chloroplasts that are composed of protein and lipid and are the sites of the photochemical reactions of photosynthesis

Examples of thylakoid in a Sentence

Recent Examples on the Web Indirect evidence from genetics and chemical studies had previously suggested that cyanobacteria had thylakoids by this time. Will Sullivan, Smithsonian Magazine, 4 Jan. 2024 The latter is over a billion years old, which is substantially older than any previous evidence of thylakoids. John Timmer, Ars Technica, 3 Jan. 2024 Scientists understood this through other lines of evidence, such as geochemical signatures, but before this week’s study, the earliest fossils of cyanobacteria with thylakoids were only around 500 million years old. Will Sullivan, Smithsonian Magazine, 4 Jan. 2024 To search for thylakoids, the researchers obtained small cell-like bodies from sedimentary rocks in several sites. John Timmer, Ars Technica, 3 Jan. 2024 Scientists found evidence of thylakoids in the Australian fossils, which date to between 1.73 and 1.78 billion years ago, as well as the Canadian fossils, which are 900 million to 1.01 billion years old. Will Sullivan, Smithsonian Magazine, 4 Jan. 2024 Spinach is a source of thylakoids, the chlorophyll-bearing parts of green leaves. Lisa Drayer, CNN, 8 Mar. 2018

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'thylakoid.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


International Scientific Vocabulary thylak- (from Greek thylakos sack) + -oid

First Known Use

1962, in the meaning defined above

Time Traveler
The first known use of thylakoid was in 1962

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Cite this Entry

“Thylakoid.” Dictionary, Merriam-Webster, Accessed 13 Jun. 2024.

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