pineal gland   n.  A small, cone-shaped organ in the brain of most vertebrates that secretes the hormone melatonin. Also called epiphysis, pineal body, pineal organ.

Main Entry: pineal gland
Function: noun
: a small body that arises from the roof of the third ventricle and is enclosed by the pia mater and that functions primarily asan endocrine gland that produces melatonin called also pineal, pineal body, pineal organ

pineal gland n.
See pineal body.