The Collaborative International Dictionary
Thionaphthene
Thionaphthene \Thi`o*naph"thene\, n. [Thiophene + naphthalene.] (Chem.) A double benzene and thiophene nucleus, C8H6S, analogous to naphthalene, and like it the base of a large series of derivatives. [Written also thionaphtene.]
Wiktionary
thionaphthene
n. (context organic compound English) A two-ringed aromatic heterocycle consisting of a benzene ring fused to one of thiophene; any derivative of this compound