• Webster's Revised Unabridged Dictionary
    • n Toluidine (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.☞ It is used in the aniline dye industry, and constitutes the essential nucleus or radical of those dyes.
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Century Dictionary and Cyclopedia
    • n toluidine A name of three compounds, CH3C6H4NH2, formed by the reduction of the corresponding nitrotoluenes. They are all colorless, and are used in the regeneration of vulcanized rubber and in the preparation of certain so-called aniline dyes. The ortho- (1,2-) and the meta- (1,3-) derivatives are liquids, boiling at 197° C. and 199° C. respectively. The para- (1,4-) derivative crystallizes in plates, melts at 45° C., and boils at 198° C.
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In literature:

Combination of A-Naphthol with Toluidine.
"The Dyeing of Cotton Fabrics" by Franklin Beech
By a similar process toluene is converted into nitrotoluene, and the latter into toluidine.
"Coal" by Raphael Meldola

In science:

The evolution of the glassy dynamics of m-toluidine was measured for temperatures decreasing from 295K to 250K.
The Cole-Cole Law for Critical Dynamics in Glass-Forming Liquids