cretin

   The technical medical sense of cretin is a person whose mental and physical development has been stopped in early childhood because of a weakness in the thyroid. When the word occurs vocatively, however, it is invariably used to mean ‘fool’, ‘idiot’, in a far more general sense. Most speakers would be unable to define it technically, and would be unaware of its historical and etymological origins.

   Cretins were at one time unfortunate creatures who lived mainly in Alpine valleys. ‘Cretin’ Originally meant ‘Christian’, a word meant to draw attention to the fact that cretins were human beings, not brute animals. Examples of the watered down use of ‘you cretin’ as a relatively mild insult occur in, e.g., The Sleepers of Erin, by Jonathan Gash.