know-nothing (n.) Look up know-nothing at Dictionary.com
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.