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 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 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

• 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

In addition to severe mental illness, Bonin had been diagnosed with kidney disease that required dialysis. —Jeff McDonald, San Diego Union-Tribune, 19 July 2025

Doctors had also found a blood clot in one of Kate's kidney veins, which accounted for the pain in her back. —Hannah Sacks, People.com, 18 July 2025

People with kidney disease are at higher risk of developing it after consuming too much potassium. —Maggie O'Neill, Verywell Health, 18 July 2025

Doctors must rule out serious causes of leg swelling, such as heart problems, kidney disease or blood clots. —Eleanor Pringle, Fortune, 18 July 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