Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
per-salsus, a, um, adj., very witty, Cic. de Or. 2, 69, 279.
Hence, adv.: per-salsē, very wittily: gratias agere, Cic. Q. Fr. 2, 15, 3.