|thīō+ noun
Etymology: International Scientific Vocabulary thi- + phenol
1. : a mobile liquid mercaptan C 6 H 5 SH with a smell like garlic and with acid properties somewhat stronger than those of phenol that may be formed by the action of phosphorus pentasulfide on phenol but that is better synthesized by reduction of benzene-sulfonyl chloride — called also phenyl mercaptan
2. : an aromatic mercaptan (as thiophenol)