Lacking intelligence or good sense; foolish or silly.
From Old English 'wit' (mind, intelligence, sense) + '-less' (without). Literally means 'without wit' and has been used since the 1500s to describe foolish behavior.
The word 'wit' itself originally just meant 'mind' or 'mental faculties,' but evolved to mean clever humor—so 'witless' originally meant mindless, but now can imply both stupid AND unfunny.
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