Mercaptans are a traditional term abandoned by IUPAC, synonymous with thiols, a sulfur-containing organic compound with the general formula R-SH where R is any radical. This term is still widely used.
Generalic, Eni. "Mercaptans." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
Glossary
Periodic Table