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kidney

American  
[kid-nee] / ˈkɪd ni /

noun

plural

kidneys

  1. Anatomy. either of a pair of bean-shaped organs in the back part of the abdominal cavity that form and excrete urine, regulate fluid and electrolyte balance, and act as endocrine glands.

  2. Zoology. a corresponding organ in other vertebrate animals or an organ of like function in invertebrates.

  3. the meat of an animal's kidney used as food.

  4. constitution or temperament.

    He was a quiet child, of a different kidney from his boisterous brothers.

  5. kind, sort, or class.

    He is only at ease with men of his own kidney.
kidney British  
/ ˈkɪdnɪ /

noun

  1. either of two bean-shaped organs at the back of the abdominal cavity in man, one on each side of the spinal column. They maintain water and electrolyte balance and filter waste products from the blood, which are excreted as urine

  2. the corresponding organ in other animals

  3. the kidneys of certain animals used as food

  4. class, type, or disposition (esp in the phrases of the same or a different kidney )

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
kidney Scientific  
/ kĭd′nē /

  1. Either of a pair of organs that are located in the rear of the abdominal cavity in vertebrates. The kidneys regulate fluid balance in the body and filter out wastes from the blood in the form of urine. The functional unit of the kidney is the nephron. Wastes filtered from the blood by the nephrons drain into the ureters, muscular tubes that connect each kidney to the bladder.

  2. See also nephron

Other Word Forms

  • kidneylike adjective

Etymology

Origin of kidney

1275–1325; Middle English kidenei, kidenere (singular), kideneres, kideneren (plural); origin uncertain; perhaps a compound based either on nere (singular), neres (plural) kidney ( Old English *nēore; compare Old High German nioro, Old Norse nȳra ); or ei (singular), eiren (plural) egg 1, Old English ǣg (singular), ǣgru (plural) (by association with the organ's shape); for the first element compare dial. kid pod (akin to cod 2 )

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

One patient required treatment for hemolytic uremic syndrome, a serious kidney complication.

From Los Angeles Times • Apr. 2, 2026

Despite his early exit, Littler remains top of the table while Van Veen - still recovering after missing night seven in Dublin because he needed surgery to remove kidney stones - is up to fifth.

From BBC • Apr. 2, 2026

Growth drivers include increasing chronic kidney disease prevalence, better affordability supported by public health programs, and rising disposable incomes.

From The Wall Street Journal • Apr. 1, 2026

Some salt substitutes contain potassium, which can build up to dangerous levels in people with kidney disease or those taking certain medications or supplements.

From Science Daily • Mar. 31, 2026

“No? Here? Does this hurt? So. Well, I think you just need a kidney flushing.”

From "East of Eden" by John Steinbeck

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.