A nurse holding a model of the human kidney.
An organ in your lower back that allows you to expel waste by creating urine is an example of a kidney.
- either of a pair of glandular organs in the upper abdominal cavity of vertebrates, which separate water and waste products of metabolism from the blood and excrete them as urine through the bladder
- the kidney of an animal, used as food
- disposition; temperament
- class; kind; sort: persons of the wrong kidney
Origin of kidneyMiddle English kidenei from uncertain or unknown; perhaps
- Anatomy Either one of a pair of organs in the dorsal region of the vertebrate abdominal cavity, functioning to maintain proper water and electrolyte balance, regulate acid-base concentration, and filter the blood of metabolic wastes, which are then excreted as urine.
- The kidney of certain animals, eaten as food.
- An excretory organ of certain invertebrates.
- Temperament; kind: a person of the same kidney.
Origin of kidneyMiddle English kidenei
From Middle English kednei, kidenei, from earlier kidnēre, kidenēre (“kidney”). Of obscure origin and formation. Probably a compound consisting of Middle English *kid, *quid (“belly, womb”), from Old English cwiþ, cwiþa (“belly, womb, stomach”) + Middle English nēre (“kidney”), from Old English *nēora (“kidney”), from Proto-Germanic *neurô (“kidney”), from Proto-Indo-European *negʷh-r- (“kidney”). If so, then related to Scots nere, neir (“kidney”), Dutch nier (“kidney”), German Niere (“kidney”), Danish nyre (“kidney”), Swedish njure (“kidney”).
Alternate etymology traces the first element to Old English cēod, codd (“sack, scrotum”), from Proto-Germanic *keudō (“sack”) as the terms for testicle and kidney were often interchangeable in Germanic (compare Old High German nioro (“kidney", also "testicle”), Old Swedish vig-niauri (“testicle”). More at codpiece.