n, often cap G&V  :  any of several dyes (as crystal violet) or dye mixtures that consist of one or more methyl derivatives of pararosaniline : esp  :  a dark green or greenish mixture used medicinally that contains not less than 96 percent of the derivative of pararosaniline containing six methyl groups in each molecule and is used esp. as a bactericide, fungicide, and anthelmintic .
 
 
 
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