ETYM French urine, Latin urina; akin to urinari to plunge under water, to dive, Greek uron urine.
Amber-colored fluid filtered out by the kidneys from the blood. It contains excess water, salts, proteins, waste products in the form of urea, a pigment, and some acid.
The kidneys pass it through two fine tubes (ureters) to the bladder, which may act as a reservoir for up to 0.7 l/1.5 pt at a time. In mammals, it then passes into the urethra, which opens to the outside by a sphincter (constricting muscle) under voluntary control. In reptiles and birds, nitrogenous wastes are discharged as an almost solid substance made mostly of uric acid, rather than urea.
Liquid excretory product; SYN. piss, pee, piddle, weewee, water.