# melatonin

> English word · Noun · IPA /ˌmɛləˈtəʊnɪn/ · frequency rank #30,499

## Definitions
1. A hormone, related to serotonin, that is secreted by the pineal gland, and stimulates colour change in the skin of reptiles, and is involved in the sleep and wake and reproductive cycles in mammals.
2. Any material similar in its chemistry and effect to the natural hormone.

## Etymology
From mela- + tone + -in, ultimately from Ancient Greek μέλας (mélas, “black, dark”).

## Easily confused with
- **melanin** (https://plainspell.com/en/vs/melanin-vs-melatonin)

## Common misspellings (13)
`emlatonin`, `mealtonin`, `melaotnin`, `melatnoin`, `melatoinn`, `melatoninn`, `melatonni`, `melatonnin`, `melattonin`, `mellatonin`, `meltaonin`, `mleatonin`, `mmelatonin`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/melatonin