melatonin

noun

mel·​a·​to·​nin ˌme-lə-ˈtō-nən How to pronounce melatonin (audio)
: a vertebrate hormone that is derived from serotonin, is secreted by the pineal gland especially in response to darkness, and has been linked to the regulation of circadian rhythms

Examples of melatonin in a Sentence

Recent Examples on the Web However, information on the long-term effects of melatonin use in children is limited and parents are advised to exercise caution. —Saman Shafiq, USA TODAY, 20 May 2024 A day care owner and three of her employees have been arrested after allegedly sprinkling melatonin on children's food, police say. —Jon Haworth, ABC News, 16 May 2024 See all Example Sentences for melatonin 

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

Word History

Etymology

mela-, extracted from Greek melan-, mélās "black, dark" + -tonin (in serotonin); so named because the hormone can lighten skin color in animals by reversing the effect of melanocyte-stimulating hormones — more at melano-

Note: The word was probably introduced in the first published description of the hormone's isolation: Aaron B. Lerner, et al., "Isolation of melatonin, the pineal gland factor that lightens melanocytes," Journal of the American Chemical Society, vol. 80, no. 10 (May 20, 1958), p. 2587.

First Known Use

1958, in the meaning defined above

Time Traveler
The first known use of melatonin was in 1958

Dictionary Entries Near melatonin

melastome

melatonin

melatope

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Cite this Entry

“Melatonin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/melatonin. Accessed 1 Jun. 2024.

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Kids Definition

melatonin

noun
mel·​a·​to·​nin ˌmel-ə-ˈtō-nən How to pronounce melatonin (audio)
: a hormone that is secreted by the pineal gland especially in response to darkness and has been linked to the regulation of bodily functions or activities (as sleep) that occur in approximately 24 hour cycles

Medical Definition

melatonin

noun
mel·​a·​to·​nin ˌmel-ə-ˈtō-nən How to pronounce melatonin (audio)
: a vertebrate hormone C13H16N2O2 that is derived from serotonin, is secreted by the pineal gland especially in response to darkness, and has been linked to the regulation of circadian rhythms

More from Merriam-Webster on melatonin

Britannica.com: Encyclopedia article about melatonin

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