Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
insulsĭtas, ātis, f. [insulsus]. tastelessness, insipidity, silliness, absurdity (class.): insipientia insulsitasque, Plaut. Mil. 3, 3, 11: villae, Cic. Att. 13, 29: harum rerum, id. ib. 5, 11 init.: Graecorum, id. Rab. Post. 13: orationis, id. Brut. 82, 284; Quint. 5, 13, 38.