barbituric acid bar·bi·tu·ric acid (bär'bĭ-tur'ĭk, -tyur'-)
n.
An organic acid used in the manufacture of barbiturates.
an organic compound of the pyrimidine family, a class of compounds with a characteristic six-membered ring structure composed of four carbon atoms and two nitrogen atoms, that is regarded as the parent compound of the barbiturate drugs. It is used in the production of riboflavin, a nutritional factor (see vitamin B2).