Wiktionary
quarter-witted
a. Having, or displaying half the mental capacity of a half-wit.
Usage examples of "quarter-witted".
But even as he spoke there was a muffled thumping, two or three vile oaths, and Stephen came in on his bandaged feet, his elbows supported by his servant, a quarter-witted but docile and sweet-natured Marine, and Killick.