Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
infectōrĭus, a, um, adj. [inficio], that serves for dyeing (late Lat.): alumen, Marc. Emp. 4.
Subst.: infectōrĭum, ĭi, n., a dye-house, Gr. βαφεῖον, Gloss. Philox.