toluenesulfonic acid
noun
tol·u·ene·sul·fon·ic acid
variants:
or British toluenesulphonic acid \ ˌtäl-yə-ˌwēn-səl-ˌfän-ik- 
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Medical Definition of toluenesulfonic acid
: any of three isomeric crystalline oily liquid strong acids CH3C6H4SO3H of which the para isomer has important use in organic synthesis (as of dyes)