noun a mentally slow person US, 1976⇨ See: BERK

noun a fool. Almost certainly a reduction of the rhyming slang BERKSHIRE HUNT or BERKELEY HUNT (a CUNT) yet so widely used that the original sense has almost been lost; there is a suggestion that 'berk' may be a diminution of BERKELEYS (the female breasts), thus TIT (a fool) UK, 1936