Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
per-bĕnĕ, adv., very well: prandi perbene, Potavi, Plaut. Men. 5, 9, 81: pol ego haud a pecuniā perbene, id. Aul. 2, 2, 9: loqui Latine, Cic. Brut. 28, 108: Fortunam fecisse, quando, etc., Liv. 45, 3, 5.