Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
per-sanctus, a, um, adj., very sacred or holy: CONIVX, Inscr. Afr. ap. Rénier, 4414.
Hence, adv.: per-sanctē, very sacredly or religiously: dejerare, to swear solemnly, Ter. Hec. 5, 2, 5: jurare, Suet. Tib. 10; id. Ner. 35.