: a member of a former organization (the America First Committee) that opposed U.S. entry into World War II
2
: an American who believes that the interests of the U.S. should always take priority over those of other countries and that the U.S. should avoid involvement in international affairs
Meanwhile, grass-roots conservative activists, from Christian social conservatives who felt betrayed by Carter to America-firsters outraged by the loss of the Panama Canal, had mobilized like never before …—Steve Kornacki, New York Observer, 26 June 2008