Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
perpōtātĭo, ōnis, f. [perpoto], a continued drinking, a drinking-bout: biduo duabusque noctibus perpotationem continuare, Plin. 14, 22, 28, § 145: intemperantissimae perpotationes, Cic. Pis. 10, 22: vomitiones ac rursus perpotationes, Plin. 29, 1, 8, § 27.