kidney

kid·ney

noun \ˈkid-nē\

plural kidneys

Definition of KIDNEY

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 4¹⁄₂ inches (11¹⁄₂ 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 the pelvis of the kidney whence it is conveyed by the ureter to the bladder—compare mesonephros, metanephros, pronephros

2

: any of various excretory organs of invertebrate animals

Illustration of KIDNEY