fluorescein

noun

fluo·​res·​ce·​in flu̇-ˈre-sē-ən How to pronounce fluorescein (audio)
flȯ-
: a yellow or red crystalline dye C20H12O5 with a bright yellow-green fluorescence in alkaline solution

Example Sentences

Recent Examples on the Web Researchers dumped a dye, fluorescein, into the wells and monitored the marine waters along the beaches. Warren Cornwall, Science | AAAS, 23 Apr. 2020 The polyacrylate was then bathed in molecules of fluorescein, an orange dye with a yellow-green fluorescence that's commonly used as a scientific marker. David Grossman, Popular Mechanics, 18 Dec. 2018 With the fluorescein in place, scientists then add an acid that hinders the negative charges in the polyacrylate gel. David Grossman, Popular Mechanics, 18 Dec. 2018 Our doctor placed yellow drops containing fluorescein sodium in his eye. Dan Olson, WIRED, 29 Sep. 2008

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

Word History

First Known Use

1871, in the meaning defined above

Time Traveler
The first known use of fluorescein was in 1871

Dictionary Entries Near fluorescein

Cite this Entry

“Fluorescein.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fluorescein. Accessed 31 Jan. 2023.

Medical Definition

fluorescein

noun
flu·​o·​res·​ce·​in -ˈes-ē-ən How to pronounce fluorescein (audio)
: a yellow or red crystalline dye C20H12O5 with a bright yellow-green fluorescence in alkaline solution that is used as the sodium salt as an aid in diagnosis (as of lesions and foreign bodies in the cornea or of brain tumors)

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