taurine A derivative of the amino acid cysteine (aminoethane sulphonic acid). Known to be a dietary essential for cats (deficient kittens are blind) and possibly essential for human beings, since the capacity for synthesis is limited, although deficiency has never been observed. In addition to its role in the eye and nervous system it is important for conjugation of the bile salts.

taurine (tor-een) n. an amino acid that is a constituent of the bile salt sodium taurocholate and also functions as a neurotransmitter in the central nervous system.