A foolish or silly person; someone who acts without much sense or intelligence.
From the 1590s-1600s, likely a playful variant of 'innocent' (someone naïve or simple), or possibly from the name 'Ninon.' It's an early insult that survives mainly in children's literature and older works.
The word 'ninny' is mostly obsolete now, but it shows how insults with playful sounds (like 'nincompoop' and 'nitwit') were created by adding silly-sounding suffixes—a linguistic pattern that makes the word itself sound foolish before you even know what it means.
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