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

Her kidneys weren’t keeping up. —Hilke Schellmann, Scientific American, 17 Feb. 2026

Staying hydrated helps the kidneys function properly. —Merve Ceylan, Health, 17 Feb. 2026

George Washington Long before modern steakhouses, America's first president reportedly favored beefsteak and kidney pie, which was a popular 18th-century Anglo-American dish, according to historical accounts. —Deirdre Bardolf, FOXNews.com, 16 Feb. 2026

These nerves transmit signals between the kidneys and brain, influencing blood pressure regulation. —Memorialcare, Oc Register, 16 Feb. 2026

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