moron

The word 'moron' entered English in the early 20th century via scientific terminology, specifically from the Greek 'mōron', the neuter form of 'mōros', meaning 'foolish, dull, or sluggish'. It was first adopted as a clinical term in psychology to denote a specific category of intellectual disability. Over time, its usage shifted from a technical medical classification to a general and offensive term for a person perceived as very stupid or foolish. This evolution reflects a common pattern where specialized scientific vocabulary migrates into everyday pejorative slang, shedding its precise definition but retaining its core association with a lack of intelligence.

This word is a simplex loanword from Greek, adopted as a whole into English. It originates from the Greek neuter noun 'mōron', meaning 'foolish, dull'.