rho·​dop·​sin rō-ˈdäp-sən How to pronounce rhodopsin (audio)
: a red photosensitive pigment in the retinal rods of the eye of most vertebrates that is important in vision in dim light

called also visual purple

Examples of rhodopsin in a Sentence

Recent Examples on the Web Without adequate levels of Beta-Carotene, the production of rhodopsin can be impaired, leading to vision problems such as night blindness. Discover Magazine, 30 June 2023 But the experiment may not reveal much about how rhodopsin use evolved in nature. Byelizabeth Pennisi, science.org, 18 Apr. 2023 In the deep sea, the rhodopsin pigments in whale shark eyes are specifically calibrated to see blue light—the only color that reaches these depths. Byjack Tamisiea, science.org, 24 Mar. 2023 Our eyes adapt badly to darkness, and our night vision—which is activated by the pigment protein rhodopsin—takes a long while to turn on, as anyone who leans back on a car roof to watch the evening stars knows. Adam Gopnik, The New Yorker, 20 Feb. 2023 Fun fact: Unlike others of its kind, A. hoosieri lacks a debilitating mutation in the rhodopsin gene, which is an important gene for vision. Brenda Poppy, Discover Magazine, 10 Dec. 2014 Vitamin A is also a component of the protein rhodopsin, which allows the eye to see in the dark. Korin Miller, Good Housekeeping, 12 Nov. 2021 All rods contain the same type of photopigment, called rhodopsin. Gabriel A. Silva, Forbes, 20 May 2021 Altogether, researchers have uncovered about 1000 other varieties of the proteins in various animals and microbes since rhodopsin was discovered more than 150 years ago. Mitch Leslie, Science | AAAS, 2 Apr. 2020 See More

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

Word History


borrowed from German Rhodopsin, from rhod- rhod- + Greek ópsis "appearance, sight, vision" + German -in -in entry 1 — more at optic entry 1

Note: Term introduced by the German physiologist Wilhelm Kühne (1837-1900) and his assistant August Ewald (1849-1924) in "Untersuchungen über den Sehpurpur," Untersuchungen aus dem Physiologischen Institute der Universität Heidelberg, 1. Band (1878), p. 181: "Was den Sehpurpur im Dunkel ändert, pflegt es z. Th. in derselben Weise zu thun, wie das Licht, d.h. erst eine gelbe Materie, dann farblose Substanz hervorzubringen. Der Kürze wegen und um dem Auslande unsere Bezeichnungen zugänglich zu machen, kann man sagen, Rhodopsin werde erst in Xanthopsin, dieses in Leukopsin zersetzt." ("Those things [i.e., reagents] that convert visual purple in darkness in part act in the same manner as light, that is, they first produce a yellow material, then a colorless substance. For the sake of brevity, and in order to make our designations more accessible to foreigners, we can say that rhodopsin is first broken down into xanthopsin ['visual yellow'], and this into leucopsin ['visual white'].") Kühne's selection of the combining element rhod-, usually meaning "red," is somewhat idiosyncratic, given that he is rendering German Sehpurpur ("visual purple") and not Sehrot ("visual red").

First Known Use

1878, in the meaning defined above

Time Traveler
The first known use of rhodopsin was in 1878

Dictionary Entries Near rhodopsin

Cite this Entry

“Rhodopsin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rhodopsin. Accessed 28 Feb. 2024.

Medical Definition


rho·​dop·​sin rō-ˈdäp-sən How to pronounce rhodopsin (audio)
: a red photosensitive pigment in the retinal rods of marine fishes and most higher vertebrates that is important in vision in dim light, is quickly bleached by light to a mixture of opsin and retinal, and is regenerated in the dark

called also visual purple

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