DUEL, noun [Latin]
1. Single combat; a premeditated combat between two persons, for the purpose of deciding some private difference or quarrel. A sudden fight, not premeditated, is called a rencounter. A duel is fought with deadly weapons and with a purpose to take life.
2. Any contention or contest.
DUEL, verb intransitive To fight in single combat.
DUEL, verb transitive To attack or fight singly.