Stupidity is a quality or state of being stupid, or an act or idea that exhibits properties of being stupid.[4] The root word stupid,[5] which can serve as an adjective or noun, comes from the Latin verb stupere, for being numb or astonished, and is related to stupor:[6] in Roman culture, 'the stupidus of the mimes' was a sort of 'professional buffoon - the "fall-man", the eternal he-who-gets-kicked'.[7]

According to the online Merriam-Webster dictionary, the words "stupid" and "stupidity" entered the English language in 1541. Since then, stupidity has taken place along with "fool," "idiot," "dumb," "moron," and related concepts as a pejorative appellation for human misdeeds, whether purposeful or accidental, due to absence of mental capacity.

The word "stupidest" is increasingly common in newspapers.[8][9][10]