Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
multĭbĭbus, a, um, adj. [multus-bibo], much-drinking (ante- and post-class.): lena, Plaut. Curc. 1, 1, 77: anus, id. Cist. 1, 3, 1: heros, Macr. S. 5, 21.