nitwit

noun

Etymology: First attested in the 1910s in the US Northeast. Likely from German nit, dialect form of nichts (“nothing”), or Yiddish ניט (nit), dialect form of נישט (nisht, “no”), although some dictionaries give the alternative etymology nit (“louse egg; something very small”) + wit.

1. A scatterbrained or stupid person.

   “If you don't remember you are a nitwit. If you do answer, well, you know what the penalty is for perjury.”

   “"Don't be a nitwit, honey!" says Adele. "Here, let me open the door! Ma be I did leave them lights on, though it ain't ike me!"”