Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prō-sĕda, ae, f. [sedeo] (she who sits in public), a common prostitute (perh. only Plaut.), Plaut. Poen. 1, 2, 53; cf.: prosedas meretrices Plautus appellat, quod ante stabula sedeant. Eaedem et prostibulae, Paul. ex Fest. p. 226 Müll.