pineal gland

American  

noun

1. a small, cone-shaped endocrine organ in the posterior forebrain, secreting melatonin and involved in biorhythms and gonadal development.

---

pineal gland British  

noun

1. Technical names: epiphysis.   epiphysis cerebri.  a pea-sized organ in the brain, situated beneath the posterior part of the corpus callosum, that secretes melatonin into the bloodstream

---

pineal gland Scientific  

1. A small gland located near the brain and primarily involved in the production and secretion of the hormone melatonin, which regulates circadian rhythms in many animals, including humans.

---

Etymology

Origin of pineal gland

First recorded in 1705–15

Example Sentences

It has become the pineal gland, a small structure deep in the brain.

From Science Daily • Apr. 27, 2026

But in the case of cysts of the pineal gland, there is a large amount of information on the web which prompts patients to seek surgery for minor and often unrelated symptoms.

From BBC • Dec. 4, 2024

These supplements, including sugary gummies, typically offer much higher doses than what the pineal gland produces to help shift circadian rhythm to night mode.

From Scientific American • May 5, 2023

Melatonin is a naturally occurring hormone produced by the pineal gland, a small structure at the center of the brain.

From Washington Post • Dec. 19, 2022

Descartes solved this problem as best he could by claiming that mind acted on the body through the pineal gland.

From "The Invention of Science" by David Wootton