Kidneys

n. one of a pair of organs that filters metabolic wastes from the blood; temperament; kind, sort, class

The kidneys are organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. The medical field that studies the kidneys and diseases of the kidney is called nephrology. The prefix nephro- meaning kidney is from the Ancient Greek word nephros (νεφρός); the adjective renal meaning related to the kidney is from Latin rēnēs, meaning kidneys.
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Kidneys A pair of organs located on each side of the spine in the lower back area. They excrete, or get rid of, urine. Mentioned in: Bed-Wetting [more]Kidneys - Community and Resources

Noun
1. either of two bean-shaped excretory organs that filter wastes (especially urea) from the blood and excrete them and water in urine; urine passes out of the kidney through ureters to the bladder
(hypernym) excretory organ, urinary organ
(part-holonym) urinary tract
(part-meronym) nephron, uriniferous tubule

(pl. )
of Kidney