Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
mūnĭcĭpātus, ūs, m. [municeps], citizenship (eccl. Lat.): πολίτευμα, id est municipatus, Tert. adv. Marc. 3, 24; Inscr. Orell. 3702.