Etymology
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ignoramus (n.)
1570s, originally an Anglo-French legal term (early 15c.), from Latin ignoramus "we take no notice of, we do not know," first person plural present indicative of ignorare "not to know, take no notice of" (see ignorant). The legal term was one a grand jury could write on a bill when it considered the prosecution's evidence insufficient. Sense of "ignorant person" (1616) came from the title role in George Ruggle's 1615 play in Latin satirizing the ignorance of common lawyers. The plural is ignoramuses as it never was a noun in Latin.
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know-nothing (n.)
1827, "ignoramus," from know (v.) + nothing. As a U.S. nativist political party, active 1853-56, the name refers to the secret society at the core of the party, about which members were instructed to answer, if asked about it, that they "know nothing." The party eventually merged into the Republican Party. Related: Know-nothingism.
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dunce (n.)

"dullard, dolt, ignoramus," 1570s, from earlier Duns disciple, Duns man (1520s) "follower of John Duns Scotus" (c. 1265-1308), Scottish scholar of philosophy and theology supposed to have been born at Duns in Berwick. His followers, the Scotists, had control of the universities until the Reformation. By 1520s, humanist reaction against medieval theology had singled him out as the type of the hairsplitting scholastic. It became a general term of reproach applied to obstinate or sophistical philosophical opponents by 1520s, then by 1570s it was extended to any dull-witted student. Dunce's cap is attested by 1792 (compare foolscap).

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