imbecile

A person with limited mental capacity who can perform tasks and think only like a young child, in medical circles meaning a person who lacks the capacity to develop beyond the mental age of a normal five- to seven-year-old child.

It is an offence for a man to have unlawful sexual intercourse with a woman whom he knows to be an idiot or imbecile.

A fool, an idiot.

VLADIMIR: Because he wouldn't save them. / ESTRAGON: From hell? / VLADIMIR: Imbecile! From death.

“A rat picked up a drink can and threw it at me?” yelled Mr Big. “A big rat, guv’nor? One of them super-rats?” suggested Thumbs. “It landed on my head, you imbecile!”

Destitute of strength, whether of body or mind; feeble; impotent; especially, mentally weak.

hospitals for the imbecile and insane

And then that imbecile crowd down on the deck started their little fun, and I could see nothing more for smoke.