(initial capital letters) U.S. History. a member of a political party (American party or Know-Nothing party) prominent from 1853 to 1856, whose aim was to keep control of the government in the hands of native-born citizens: so called because members originally professed ignorance of the party's activities.
4.
a person whose anti-intellectualism, xenophobia, and other political attitudes recall the Know-Nothings.