Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† pĕrĭnaeon and pĕrĭnēon, i, n., = περιναιον, περινεον, the space between the sexual parts and the fundament, the perineum (post-class.), Cael. Aur. Tard. 5, 4, 66; 68; 5, 3, 59.