the.com/dunce

means A person regarded as slow-witted or incapable of learning — often someone just stuck wearing the label unfairly.

from From 'Duns', after John Duns Scotus, a razor-sharp medieval theologian whose followers (the 'Dunsmen' or 'Duncemen') clung to his intricate logical methods even as Renaissance humanists rose up against old scholastic philosophy. Those humanist critics mocked Scotus's disciples as hairsplitting obstructionists resistant to new learning, and 'dunce' curdled from a badge of a sharp philosophical school into a slur for a thickheaded fool — one of history's great reputational reversals.