half-wit

[half-wit, hahf-]

a person who is feeble-minded.

a person who is foolish or senseless; dunderhead.

Origin of half-wit

First recorded in 1670–80

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Naomi Watts plays Diana as a sweet-natured, wistful, half-wit.
Princess Diana Was the Girlfriend From Hell. Why Is This Movie So Boring?
Tina Brown
November 4, 2013

"For the family," was Cleena's watchword, and it had already become the half-wit's.
Reels and Spindles
Evelyn Raymond
"No half-wit about you," admiringly quoth the carpenter's mate.
Blackbeard: Buccaneer
Ralph D. Paine
Beside being a half-wit he had something the matter with his legs.
Poor White
Sherwood Anderson
Allie Mulberry the half-wit was one of the highlights of life in the town.
Poor White
Sherwood Anderson
For what the half-wit did was what he had seen these others do.
The Broken Gate
Emerson Hough

Word Origin and History for half-wit

1670s, originally "a would-be wit whose abilities are mediocre;" sense of "simpleton" (one lacking all his wits) is first attested 1755.

Half-wits are fleas; so little and so light,
We scarce could know they live, but that they bite.
[Dryden, "All for Love"]

Phrase out of half wit "half out of one's mind" was in Middle English (late 14c.). Half-witted "lacking common sense" is from 1640s.