a small, cone-shaped endocrine organ in the posterior forebrain, secreting melatonin and involved in biorhythms and gonadal development.
Origin of pineal gland
First recorded in 1705–15
Also called epiphysis.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for pineal gland
a pea-sized organ in the brain, situated beneath the posterior part of the corpus callosum, that secretes melatonin into the bloodstreamTechnical names: epiphysis, epiphysis cerebri
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Medicine definitions for pineal gland
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Science definitions for pineal gland
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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.