kidney

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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Kidney /kid·ney/ either of the two organs in the lumbar region that filter the blood, excreting the end-products of body metabolism in the form of [more]Kidney - 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

(n.)
Habit; disposition; sort; kind.
  

(n.)
A waiter.
  

(n.)
A glandular organ which excretes urea and other waste products from the animal body; a urinary gland.