Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† cyăthisso, āre, v. n., = κυαθίζω, to fill a cyathus, Plaut. Men. 2, 2, 29; Macr. de Diff. 41, 8; Auct. de Verb. 8, § 14 Jan.