Noun
trimethylbenzene (countable and uncountable, plural trimethylbenzenes)
English Wikipedia has an article on:trimethylbenzeneWikipedia
(chemistry) Any of three isomeric chemical compounds: 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene (pseudocumene), and 1,3,5-trimethylbenzene (mesitylene).