Cretin
late 18th century: from French crétin, from Swiss French crestin ‘Christian’ (from Latin Christianus ), here used to mean ‘human being’, apparently as a reminder that, though deformed, cretins were human and not beasts.
wiktionary
From French crétin(“cretin, idiot”), from crestin, an Alpine dialectal form of chrétien, from Latin christiānus in the lost sense of “anyone in Christendom”, often with a sense of “poor fellow”. Doublet of Christian.
etymonline
cretin (n.)
1779, from French crétin (18c.), from Alpine dialect crestin, "a dwarfed and deformed idiot" of a type formerly found in families in the Alpine lands, a condition caused by a congenital deficiency of thyroid hormones. The word is of uncertain origin. By many it has been identified with Vulgar Latin *christianus "a Christian," a generic term for "anyone," but often with a sense of "poor fellow." Related: Cretinism (1796).
