A foolish or stupid person. In English since the 1670s — and, despite the famous theory, probably not from Latin non compos mentis.
What it really means
A nincompoop is a fool. It is one of the oldest words on this list, and it comes with one of the most repeated etymologies in English — which is probably wrong.
The word is first recorded in the 1670s, as nicompoop or ninkompoop. By the 1680s the modern spelling had arrived. In 1699 the Dictionary of the Canting Crew defined it as a Fool, also a silly soft, Uxorious Fellow — uxorious meaning a man too devoted to his wife, which was apparently its own kind of foolishness.
Now the famous story. The word looks, and sounds, a great deal like the Latin legal phrase non compos mentis, not of sound mind. Samuel Johnson noticed the resemblance. It is so neat that it gets repeated as fact.
The OED's etymologists reject it, and their reason is a single letter. The earliest forms lack the second n — nicompoop, not nincompoop. If the word had come from non compos, the n would have been there from the start. It arrived later.
Other suggestions include a proper name, such as Nicodemus or Nicholas, used for a fool. None is proven. What is certain is that the tidy Latin answer is the one the evidence argues against.
Where it comes from
Myths & misconceptions
Nincompoop comes from the Latin legal phrase non compos mentis.
It is the famous explanation, and Samuel Johnson noticed the resemblance — but the OED's etymologists reject it, because the earliest forms ('nicompoop') lack the second n that the Latin would have given.
How it connects
- Fopdoodleanother old word for a fool — and a far rarer one.
- Zounderkitemeans the same thing, but unlike nincompoop has no traceable history.
Questions people ask
- Does nincompoop come from non compos mentis?
- Probably not. The resemblance is real and Samuel Johnson noted it, but the OED rejects the link because the earliest spellings lack the second n.
- What did nincompoop originally mean?
- A fool. The 1699 Dictionary of the Canting Crew added a second sense: a 'silly soft, uxorious fellow' — a man too devoted to his wife.