Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
multĭ-fŏris, e, adj. [multus-foris], many-doored, having many entrances, openings, or holes (post-Aug.): specus, Plin. 8, 55, 81, § 218.
multĭ-fŏrus, a, um, adj. [multus-foris], having many openings, pierced with many holes (poet.): non illos … multifori delectat tibia buxi, Ov. M. 12, 158; Sen. Agam. 346.