From Latin pinea "pine cone." The endocrine gland in the center of the brain.

"E. A. Wallis Budge has noted that in some of the [Egyptian] papyri illustrating the entrance of the souls of the dead into the judgment hall of Osiris the deceased person has a pine cone attached to the crown of his head. The Greek mystics also carried a symbolic staff, the upper end being in the form of a pine cone, which was called the thyrsus of Bacchus. In the human brain there is a tiny gland called the pineal body, which is the sacred eye of the ancients, and corresponds to the third eye of the Cyclops. Little is known concerning the function of the pineal body, which Descartes suggested (more wisely than he knew) might be the abode of the spirit of man. As its name signifies, the pineal gland is the sacred pine cone in man--the eye single, which cannot be opened until CHiram (the Spirit Fire) is raised through the sacred seals which are called the Seven Churches in Asia." —Manly P. Hall, The Secret Teachings of All Ages

“The pineal gland is situated in the superior part of the brain and is the queen of all glands... The sexual glands and the pineal gland are found to be intimately correlated. The potency of the pineal gland depends upon the potency of the sexual glands. The atom of the Holy Spirit is in the pineal gland. The atom of the Son (Christ) is in the pituitary gland. The atom of the Father resides in the magnetic field of the root of the nose... The pineal gland is the window of Brahma, the diamond eye, the eye of polyvoyance.” —Samael Aun Weor, The Aquarian Message

See: The Pineal Gland