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

Chronic kidney disease can range from mild to severe, potentially causing fluid buildup and increasing the risk of high blood pressure, heart disease, stroke and premature death, according to the Centers for Disease Control and Prevention. — Shiv Sudhakar, FOXNews.com, 15 Sep. 2026

His kidney function and hydration markers didn’t return to normal for about two weeks. — Sarah Shephard, New York Times, 14 Sep. 2026

Fagel has battled three forms of cancer, an autoimmune condition and PTSD – all certified by the National World Trade Center Health Program as tied to Ground Zero, and is currently operating with one kidney and one of two lungs functioning at 25%. — Denise Crosby, Chicago Tribune, 11 Sep. 2026

This golden retriever was the last surviving dog that responded to the attacks; she was euthanized after battling kidney failure at the age of 16 in June 2016. — Pat Mueller, USA Today, 11 Sep. 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 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 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