Other forms: nitwits
A nitwit is somebody silly and scatterbrained. You nitwit, a complete nitwit, some nitwit left the gate open.
It is gentle teasing rather than real insult, which is what separates it from the harsher words for the same idea. It is mild enough for a children's book and is common in them. The wit in it means sense, and the nit probably means nothing at all.
1nounnitwitSomebody silly and scatterbrained.
“Some nitwit left the gate open, and the goats got out.”
nitwit is an insult.
Also accepted in games: knucklehead
American, from the 1910s, probably from a dialect word meaning nothing plus wit, sense.
Yiddish
ניט
German
nit
English, today
nitwit
Built from
First attested in the 1910s in the US Northeast. Likely from German nit, dialect form of nichts (“nothing”), or Yiddish ניט, dialect form of נישט (“no”), although some dictionaries give the alternative etymology nit + wit.
Etymology from Wiktionary, CC BY-SA