Modern dictionaries give the meaning : "To free from perversion, to uncorrupt." However 'perversion' here is not the recent connotation of "sexually obsessed" or "deviant" or "lascivious" - it merely applies to misdirection, misuse, or false application. The English language uses "un-" confusingly, sometimes as a synonym for "non-" : the current usage of "unperverted" is almost certainly "not perverted", as it was in Webster's 1828 dictionary.