Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
nĕpōtātus, ūs, m. [nepotor], extravagance, prodigality, profusion, Plin. 14, 4, 6, § 57; 9, 35, 56, § 114; Suet. Calig. 37 (al. nepotinis).