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Definition of melatonin

melatonin

/ˌmɛləˈtoʊnɪn/
mel · a · to · nin
Adjective:melatonergic
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melatonin Lexical Profile

melatonin Game Scores & Validity

• noun

1

A hormone secreted primarily by the pineal gland at night that regulates the body's circadian rhythm and sleep-wake cycle, also widely produced synthetically for use as a dietary supplement to aid sleep.

Example

"Exposure to bright light from electronic screens before bedtime can suppress the natural production of melatonin."

Word Nuance & Usage

Do not confuse melatonin (a hormone that regulates the sleep-wake cycle) with melanin (the pigment that gives color to skin, hair, and eyes).

• Rhymes for melatonin

• Nearby Words

melanin
melanoma
melasphaerula
melatonin
melbourne
meld
melee

Word Origin & Etymology

Coined in 1958 by dermatologist Aaron B. Lerner and his colleagues from 'melanophore' (from Ancient Greek melas, meaning 'black') and 'serotonin', referencing its ability to lighten amphibian skin and its chemical derivation from serotonin.

Cite this Entry

Wordmom. (2026). Definition of Melatonin. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/melatonin
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