What is "paratoluidine"

Toluidine \To*lu"i*dine\, 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.

Note: It is used in the aniline dye industry, and constitutes the essential nucleus or radical of those dyes.