cretin

Etymology

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.

noun

1. (pathology) A person who fails to develop mentally and physically due to a congenital hypothyroidism.
2. (by extension, derogatory) An idiot.
   When I challenged the symbolism, tried to make the professor consider the book as a piece of realism, he regarded me as if I were an absolute cretin. He got very supercilious and condescending […] 1969, Irving Wallace, The Seven Minutes