pineal gland
noun
variants or less commonly pineal or pineal body or pineal organ
: a small, typically cone-shaped structure of the brain that arises from the roof of the third ventricle, is enclosed by the pia mater, and functions primarily as an endocrine gland secreting melatonin
Note: The pineal gland varies in morphological complexity, and in some nonmammalian vertebrates (such as various reptiles) may serve a photoreceptive function.
Example Sentences
Recent Examples on the Web Certain authorities maintain that fluoride can negatively affect the pineal gland. 
Deborah Treisman, The New Yorker, 12 Sep. 2022 Melatonin is a naturally occurring hormone produced by the pineal gland that helps regulate the sleep-wake system. Elizabeth Chang, Washington Post, 20 June 2022 The pineal gland is located in the brain’s center region. The Salt Lake Tribune, 25 May 2022 Your body does normally produce melatonin, thanks in big part to your pineal gland. Bruce Y. Lee, Forbes, 7 June 2022 It’s a natural chemical produced by your pineal gland. The Salt Lake Tribune, 25 May 2022 The hormone, which is secreted by the brain’s pineal gland in the evening, serves as a signaling mechanism, said Bhanu Kolla, a professor of psychiatry and psychology, and a consultant at the Mayo Clinic’s Center for Sleep Medicine. Washington Post, 17 Dec. 2021 Taking a melatonin supplement before bed will not affect the pineal gland’s natural secretion of it. Dr. Michael Daignault, USA TODAY, 3 Dec. 2021 Melatonin is a hormone naturally produced by the brain’s pineal gland. Serena Coady, SELF, 3 Feb. 2022 See More
Deborah Treisman, The New Yorker, 12 Sep. 2022 Melatonin is a naturally occurring hormone produced by the pineal gland that helps regulate the sleep-wake system. Elizabeth Chang, Washington Post, 20 June 2022 The pineal gland is located in the brain’s center region. The Salt Lake Tribune, 25 May 2022 Your body does normally produce melatonin, thanks in big part to your pineal gland. Bruce Y. Lee, Forbes, 7 June 2022 It’s a natural chemical produced by your pineal gland. The Salt Lake Tribune, 25 May 2022 The hormone, which is secreted by the brain’s pineal gland in the evening, serves as a signaling mechanism, said Bhanu Kolla, a professor of psychiatry and psychology, and a consultant at the Mayo Clinic’s Center for Sleep Medicine. Washington Post, 17 Dec. 2021 Taking a melatonin supplement before bed will not affect the pineal gland’s natural secretion of it. Dr. Michael Daignault, USA TODAY, 3 Dec. 2021 Melatonin is a hormone naturally produced by the brain’s pineal gland. Serena Coady, SELF, 3 Feb. 2022 See More Word History
First Known Use
1712, in the meaning defined above
Medical Definition
pineal gland
noun
: a small body that arises from the roof of the third ventricle and is enclosed by the pia mater and that functions primarily as an endocrine gland that produces melatonin
called also pineal, pineal body, pineal organ