Definition of tolylene diisocyanate
: any of six isomeric esters CH3C6H3(NCO)2 of isocyanic acid or a mixture of them;
especially
: a liquid isomer made by reaction of tolylenediamine (see tolylenediamine a) and phosgene and used by itself or in a mixture with another meta isomer in making polyurethanes; 4-methyl-meta-phenylene diisocyanate
