melanin

noun

mel·​a·​nin ˈme-lə-nən 

plural melanins

: any of various black, brown, reddish-brown, reddish-yellow, or yellow pigments of living organisms that in animals are typically produced in melanocytes by the oxidation of tyrosine followed by polymerization and are found especially in skin, hair, feathers, and eyes

Scientists know that all melanin molecules consist of long chains made mostly of derivatives of the amino acid tyrosine, but the individual units of the chain connect in random order.

—Corinna Wu

Melanin performs an array of functions for modern organisms, such as camouflage, photo protection, and display.

—Margaret Jones

especially : eumelanin

Tyrosinase enzymes are needed for the manufacture of melanin, the dark pigment that forms the color base of feathers.

—Philip C. Whitford

Brown spots and birthmarks contain especially high concentrations of melanin, the substance that gives skin its color.

—USA Today

see also neuromelanin, pheomelanin

Examples of melanin in a Sentence

Recent Examples on the Web

Genetics and individual factors like melanin levels also play a role in whether that exposure leads to cancer. —Jessica Chia, SELF, 9 Apr. 2024

Ammonia and hydrogen peroxide act together to open up the cuticle, interact with melanin and keratin (those are responsible for color and texture), and change the structure in order to deposit dye. —Kaitlyn Yarborough, Southern Living, 27 Feb. 2024

Albinism is a rare non-contagious genetic condition where a lack of melanin pigment in the hair, skin and eyes leads to an individual having a pale and fair complexion. —Gus Alexiou, Forbes, 11 Feb. 2024

Ötzi is also often depicted as having lighter skin pigmentation, even though studies in the 1990s showed evidence of melanin pigment in his skin, suggestive of a darker skin tone. —Jennifer Ouellette, Ars Technica, 25 Aug. 2023

The challenge is that technology that relies on LEDs to project light onto the skin and photodetectors to record the amount of light reflected can have a tough time with melanin, which alters skin light absorption. —Frederick Melo, Twin Cities, 14 Jan. 2024

To that end, some genetic variants produce more melanin, which leads to a darker color, while other genetic variants produce less melanin, which leads to lighter colored eyes, Stevens said. —Erica Lamberg, Fox News, 4 Dec. 2023

Tranexamic acid: Can be used topically or orally; there are a multitude of studies that have shown tranexamic acid slows melanin synthesis by inhibiting the plasminogen/plasmin pathways. —Kristine Thomason, Glamour, 8 Aug. 2023

By inspecting the heated feathers under a microscope and using a chemical assay to identify different types of melanin, the team found that biological pigments do leave a distinct and identifiable signature in fossils. —Riley Black, Scientific American, 14 Dec. 2023

Word History

Etymology

Greek melan-, stem of mélās "black, dark" + -in entry 1, after Italian melaina — more at melano-

Note: The term melaina was introduced in a study of squid ink by the Italian chemist Bartolomeo Bizio (1791-1862), "Ricerche chimiche sovra l'inchiostro della Seppia," Giornale di fisica, chimica, storia naturale, medicina ed arte, decade 2, tomo 8 (1825), p. 105. Bizio formed the word from Greek mélās "black" and aeí "always" because the substance he had isolated retained its color no matter what acid or other potent chemical it was exposed to ("Questo principio animal particolarissimo il fu chiamato così dal greco mélas, nero, ed aeì sempre, che vale materia sempre nera, conciossachè gli acidi, il cloro, e tutto che vi è di più potente, non bastano a mutarlo di colore.")

First Known Use

1843, in the meaning defined above

Kids Definition

melanin

noun

mel·​a·​nin ˈmel-ə-nən 

: a dark brown or black animal or plant pigment that in human beings makes some skins darker than others

Etymology

derived from Greek melan-, melas "black" — related to melancholy

Medical Definition

melanin

noun

mel·​a·​nin ˈmel-ə-nən 

: any of various black, brown, reddish-brown, reddish-yellow, or yellow pigments of living organisms that in animals are typically produced in melanocytes by the oxidation of tyrosine followed by polymerization and are found especially in skin, hair, feathers, and eyes

Scientists know that all melanin molecules consist of long chains made mostly of derivatives of the amino acid tyrosine, but the individual units of the chain connect in random order.

—Corinna Wu, Science News

especially : eumelanin

Brown spots and birthmarks contain especially high concentrations of melanin, the substance that gives skin its color.

—USA Today

Natural melanin surrounds and protects our cells not only by absorbing ultraviolet radiation, but also by scattering it and making it lose energy, rendering it harmless.

—Rowann Gilman, Prevention

see also neuromelanin, pheomelanin