Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
trĭvĭālis, e, adj. [trivium; prop. that is in or belongs to the cross-roads or public streets; hence, transf.], that may be found everywhere, common, commonplace, vulgar, ordinary, trivial (post-Aug.): trivialis scientia, Quint. 1, 4, 27: verba (opp. splendide atque adornate declamare), Suet. Rhet. 6: ludii ex circo, id. Aug. 74: carmen, Juv. 7, 55: mos, Calp. Ecl. 1, 28.