kidney

noun

kid·​ney ˈkid-nē 

plural kidneys

1

a

: 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 4½ inches (11½ 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 from which it is conveyed by the ureter to the bladder

b

: any of various excretory organs of invertebrate animals

2

: the kidney of an animal eaten as food

3

: sort or kind especially with regard to temperament

… a nice helpful guy, of a different kidney entirely from the … Secret Police …

—Paula Lecler

Synonyms of kidney

• type
• kind
• stripe
• sort
• genre
• breed
• variety

Examples of kidney in a Sentence

a patient with a damaged kidney

her new boyfriend is of a different kidney than what she usually dates

Recent Examples on the Web

While the arrest did cause severe kidney and liver damage, ECMO afforded a long enough runway for dialysis and other treatments that gradually brought those vital organs back into functional condition. —Paul Sisson, San Diego Union-Tribune, 25 Dec. 2025

Doctors later found that the kidney was covered in a fungus. —Raven Brunner, PEOPLE, 25 Dec. 2025

The other organ that’s common for living donations is the kidney. —Laylan Connelly, Oc Register, 24 Dec. 2025

Fulks has chronic kidney disease, degenerative disc disease and requires a catheter to urinate. —Chiara Eisner, NPR, 23 Dec. 2025

Word History

Etymology

Middle English

First Known Use

14th century, in the meaning defined at sense 1a

Phrases Containing kidney

• kidney bean
• kidney stone
• polycystic kidney disease

Kids Definition

kidney

noun

kid·​ney ˈkid-nē 

plural kidneys

1

: either of a pair of oval to bean-shaped organs located in the back part of the abdomen near the spine that give off waste products in the form of urine

2

: an organ of an invertebrate animal that gives off waste

Medical Definition

kidney

noun

kid·​ney ˈkid-nē 

plural kidneys

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 renal pelvis whence it is conveyed by the ureter to the bladder compare mesonephros, metanephros, pronephros

2

: any of various excretory organs of invertebrate animals