a. (Chem.) Pertaining to, or designating, one of three metameric acids, CH3.C6H4.CO2H, which are related to toluene and analogous to benzoic acids. They are white crystalline substances, and are called respectively orthotoluic acid, metatoluic acid, and paratoluic acid. [ 1913 Webster ]

n. (Chem.) A complex double tolyl and toluidine derivative of glycocoll, obtained as a white crystalline substance. [ 1913 Webster ]

n. (Chem.) Any one of three metameric amido derivatives of toluene analogous to aniline, and called respectively orthtoluidine, metatoluidine, and paratoluidine; especially, the commonest one, or paratoluidine, which is obtained as a white crystalline substance. [ 1913 Webster ]

☞ It is used in the aniline dye industry, and constitutes the essential nucleus or radical of those dyes. [ 1913 Webster ]