What is "thiopyran"

n. (context organic compound English) An unsaturated six-membered heterocycle consisting of five carbon atoms. one sulfur atom and two double bonds

Thiopyran is a heterocyclic compound with the chemical formula CHS. There are two isomers, 2H-thiopyran and 4H-thiopyran, which differ by the location of double bonds. Thiopyrans are analogous to pyrans in which the oxygen atoms have been replaced by sulfur atoms.