Barbituric acid : A white, crystalline substance, CH2(CO.NH)2.CO, derived from alloxantin, also from malonic acid and urea, and regarded as a substituted urea.

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Taxonomy
Barbituric acid, 1,3, free encyclopedia, compound, pyrimidine, urea, search, trione, diazine, Hydroxy, dioxo, Identifiers, N1, c7, 2-1-3, H2, 6,7,8, g/mol.

Defination from the web:
Barbituric acid or malonylurea or 4-hydroxyuracil is an organic compound based on a pyrimidine heterocyclic skeleton. It ... Using the Knoevenagel condensation reaction, barbituric acid can form a large variety of barbiturate drugs that behave as central nervous system depressants. ...