bout, by-election, caucus, closed primary, congressional election, contest, contested election, decathlon, defluxion, direct primary, discharge, double-header, doubles, drain, drainage, effluence, efflux, effluxion, effusion, election, event, exhalation, exhaust, flowoff, foursome, game, games of chance, general election, go, gush, mandatory primary, match, meet, nonpartisan primary, open primary, optional primary, outfall, outflow, outflowing, outpour, outpouring, partisan election, pentathlon, play, play-off, preference primary, presidential election, presidential preference primary, presidential primary, primary, primary election, race, referendum, runoff election, runoff primary, singles, sport, threesome, twosome

For further exploring for "runoff" in Webster Dictionary Online