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thiol thi·ol (thī'ôl', -ōl')
A mixture of sulfurated and sulfonated petroleum oils that is purified with ammonia and is used in the treatment of skin diseases.
any of a class of organic chemical compounds similar to the alcohols and phenols but containing a sulfur atom in place of the oxygen atom. Thiols are among the odorous principles in the scent of skunks and of freshly chopped onions; their presence in petroleum and natural gas is objectionable because they have disagreeable odours, interfere with catalysts used in refining processes, and produce sulfur dioxide upon combustion.