Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
per-nĭmĭus, a, um, adj., quite too great, altogether too much: nimium inter vos ac pernimium interest, Ter. Ad. 3, 3, 39; in tmesi: per parce nimium, id. And. 2, 6, 24.
Adv.: pernĭmĭum, altogether too much: interpretatio pernimium severa, altogether too severe, Dig. 48, 3, 2.