KIDNEY

noun (plural ~s) Etymology: Middle English Date: 14th century 1. one of a pair of vertebrate organs situated in the body cavity near the spinal column that excrete waste products of metabolism, in humans are bean-shaped organs about 4 1/2 inches (11 1/2 centimeters) long lying behind the peritoneum in a mass of fatty tissue, and consist chiefly of nephrons by which urine is secreted, collected, and discharged into a main cavity whence it is conveyed by the ureter to the bladder, any of various excretory organs of invertebrate animals, the ~ of an animal eaten as food, sort or kind especially with regard to temperament