thionaphthene

from The Century Dictionary.

• noun A colorless compound, , prepared from 2-amino-l-chlorostyrolene. It crystallizes in plates, melts at 30–31° C, and is volatile with steam.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Chem.) A double benzene and thiophene nucleus, C8H6S, analogous to naphthalene, and like it the base of a large series of derivatives.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun organic chemistry A two-ringed aromatic heterocycle consisting of a benzene ring fused to one of thiophene; any derivative of this compound