Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
per-jūcundus, a, um, adj., very agreeable, very pleasing: cui quidem litterae tuae perjucundae fuerunt, Cic. Fam. 1, 7, 3: disputatio, id. de Or. 2, 7, 26.
In tmesi: id mihi pergratum perque jucundum erit, Cic. Q. Fr. 3, 1, 4; so, pergrata perque jucunda, id. de Or. 1, 47, 205.
Adv.: per-jūcundē, very agreeably, very pleasantly: versari in aliquā re, Cic. Cael. 11, 25; id. Att. 13, 52, 1.