Wiktionary
thiobarbituric acid
n. (context organic chemistry English) The heterocyclic compound ''2-thioxodihydropyrimidine-4,6(1H,5H)-dione'' that is used in biochemical assay
Wikipedia
Thiobarbituric acid
Thiobarbituric acid is an organic compound and a heterocycle. It is used as a reagent in assaying malondialdehyde (the TBARS assay of lipid peroxidation).