kidney

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. 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.
2. n. The kidney of certain animals, eaten as food.
3. n. An excretory organ of certain invertebrates.
4. n. Temperment; kind: a person of the same kidney.

Century Dictionary and Cyclopedia

1. n. In anatomy, a glandular structure whose function is the purification of the blood by the excretion of urine; one of the renes or reins; a renal organ. Kidneys are of very various shapes and positions in the body, and often of loosely lobu-lated structure. In the higher vertebrates they are always paired and of compact figure, tending to become bean-shaped glands, as in man. The kidneys of man arc situated in the loins, opposite the upper lumbar vertebræ, behind the peritoneum, embedded in fat, and capped by the adrenals or suprarenal capsules. The left is somewhat higher than the right, which leaves room for the liver. They are purplish-brown in color, about 4 inches long, 2½ broad, and 1¼ thick; they weigh about 4½ ounces. Section displays an outer cortical substance, darkerand softer than the rest, consisting chiefly of uriniferous tubules and Malpighian corpuscles. (See corpuscle.) The inner or medullary substance is composed of numerous distinctly striated conical masses, or Malpighian pyramids, whose bases are directed peripherally, while their apices converge toward the interior, ending in the papillæ:, which project into the cavity of the pelvis. There are from 8 to 18 such pyramids, composed mainly of minute straight and looped uriniferous tubules, which proceed from the cortical substance to open on the papillæ. One such papilla, or a set of several papillæ, protrudes into a compartment of the general cavity called a calyx; the calyces unite in three infundibula, the beginnings of the general cavity of the kidney, the pelvis, which is also the funnel-shaped beginning of the ureter, the tube by which the urine passes to the bladder. The hilum of the kidney is the place on the median or concave side of the kidney, corresponding to the place of the scar on a bean, where the ureter goes out, and where the vessels and nerves enter. The organs are abundantly supplied with nerves, bloodvessels, and lymphatics. In its minute and essential structure the kidney consists of a great number of branching, looped, and convoluted epithelial tubes (tubuli uriniferi), terminating in dilatations, each dilatation enveloping a plexus of blood-vessels and forming a Malpighian body. These tubes, moreover.arc abundantly supplied with blood-vessels. Malpighian bodies and tubules both share in the work of secreting, but there is reason to think that the former have to do with the secretion of the water and less important parts of the urine, while the elimination of the nitrogenous waste falls on the tubular epithelium. The kidneys, or, in the singular as a collective noun, the kidney, as an important internal organ whose condition is a more or less accurate index of one's bodily health, and, as formerly thought, of one's “humor” or temperament, was formerly often spoken of (somewhat like liver, heart, bowels, stomach, etc.) with reference to one's constitution, temperament, temper, disposition, or inward feelings. As thus used in the quotation from Shakspere, the word has been misunderstood, as if meaning ‘sort’ or ‘kind,’ whence that use in later authors.
2. n. Anything resembling a kidney in shape or otherwise, as a potato.
3. n. plural The inmost parts; the reins.
4. n. A waiting-servant.
5. n. In min., a concretion shaped like a kidney.

Wiktionary

1. n. An organ in the body that filters the blood, producing urine.
2. n. This organ (of an animal) cooked as food
3. n. figuratively constitution, temperament, nature

GNU Webster's 1913

1. n. (Anat.) A glandular organ which excretes urea and other waste products from the animal body; a urinary gland.
2. n. Habit; disposition; sort; kind.
3. n. Old Cant A waiter.

WordNet 3.0

1. n. either of two bean-shaped excretory organs that filter wastes (especially urea) from the blood and excrete them and water in urine