n. Any of a class of aromatic heterocyclic compounds containing a ring of four carbon atoms and an sulphur atom; especially the simplest one, C4H4S.
the GNU version of the Collaborative International Dictionary of English
n. A sulphur hydrocarbon, C4H4S, analogous to furfuran and benzene, and acting as the base of a large number of substances which closely resemble the corresponding aromatic derivatives.
The Century Dictionary and Cyclopedia
n. A compound, C4H4S, related to benzene, and forming a large number of derivatives analogous to those of benzin.
Word Usage
"Benzene from which every trace of thiophene has not been eliminated cannot be transformed into cyclohexane."