<physiology> In mammals, a fluid excretion from the kidneys; in birds and reptiles, a solid or semisolid excretion.

In man, the urine is a clear, transparent fluid of an amber colour and peculiar odour, with an average density of 1.02. The average amount excreted in 24 hours is from 40 to 60 ounces (about 1,200 cubic centimetres). Chemically, the urine is mainly an aqueous solution of urea, salt (sodium chloride), and uric acid, together with some hippuric acid and peculiar pigments. It usually has an acid reaction, owing to the presence of acid phosphates of soda or free uric acid. Normally, it contains about 960 parts of water to 40 parts of solid matter, and the daily average excretion is 35 grams (540 grains) of urea.75 gram (11 grains) of uric acid, and 16.5 grams (260 grains) of salt. Abnormally, it may contain sugar as in diabetes, albumen as in Bright's disease, bile pigments as in jaundice, or abnormal quantities of some one or more of the normal constituents.

Origin: F. Urine, L. Urina; akin to urinari to plunge under water, to dive, Gr. Urine; cf. Skr. Var water, Icel. R drizzling rain, AS. Waer the sea.

(01 Mar 1998)