the.com/nitwit

Someone whose brain is running, but nobody's home to answer.

means A foolish or silly person who seems to lack basic sense or intelligence.

from Likely from German or Dutch roots — 'nit' (from 'nichts,' meaning 'nothing') plus 'wit' (mind or sense), so the word quite literally spells out 'nothing upstairs.' It surfaced in English in the early 20th century, possibly reinforced by American slang's fondness for punchy insults.

origin theory
possibly from German nit wit, know nothing
severity
milder than idiot, harsher than goofball
peak usage
1920s slang, still refuses to retire
classic pairing
often preceded by you absolute
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