dunce a foolish or ignorant person; originally an epithet for a follower of John Duns Scotus, whose adherents were ridiculed by 16th-century humanists and reformers as enemies of learning.
dunce's cap a paper cone formerly put on the head of a dunce at school as a mark of disgrace; the expression is recorded from the mid 19th century.

dunce †disciple of Duns Scotus; dull pedant; dullard, blockhead XVI. orig. Duns, name of John Duns Scotus (d. 1308), scholastic theologian, whose disciples formed a predominant scholastic sect at the universities until they were attacked by the humanists and reformers; occurring first in phr. Duns men, Dunces disciples.

dunce / dəns/ • n. a person who is slow at learning; a stupid person.