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

• breed
• class
• description
• feather
• genre
• ilk
• kind
• like
• manner
• nature
• order
• sort
• species
• strain
• stripe
• type
• 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

Some of these symptoms include a high fever, lethargy, hearing loss, kidney failure, confusion, brain damage, learning disabilities, coma and possibly death. —Daryl Austin, USA Today, 26 Apr. 2025

And people with kidney disease should avoid eating more protein without discussing it with their doctor. —Alice Callahan, New York Times, 25 Apr. 2025

The Eagles legend is spreading the word about how to look out for type-2 diabetes and kidney disease. —Ryan Morik, FOXNews.com, 23 Apr. 2025

Severe Kidney Disease Spinach is high in potassium, which can be dangerous for people with severe kidney disease. —Tom Gavin, EverydayHealth.com, 23 Apr. 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