A gland was a group of cells, or an organ that produced a chemical secretion.
The study of glands was known as endocrinology.
In 2372, Doctor Julian Bashir was at a loss to explain where Goran'Agar's internal supply of ketracel-white was coming from, as no glands appeared to be producing it. (DS9: "Hippocratic Oath")
List of glands
See Category:Glands