a prearranged fight with deadly weapons by two people (accompanied by seconds) in order to settle a quarrel over a point of honor
"After their heated argument about the proper way to hold a rapier, Captain Thorne challenged his rival to a formal duel complete with seconds and pistols."
any struggle between two skillful opponents (individuals or groups)
"The two chess grandmasters sat across from each other, ready to begin their mental duel without a single spoken word."
Arranged, regular combat between two private persons, often over a matter of honor.
"After years of insults exchanged at dinner parties, the two brothers finally challenged each other to a formal duel to settle their family feud once and for all."
fight a duel, as over one's honor or a woman
"In the 19th century, men often dueled over small matters"
To engage in a battle.
"The two knights stepped forward to duel for control of the castle gate."
The word comes from Medieval Latin duellum, originally meaning "war" or "fight." Its modern sense of a fight between two people arose later because people mistakenly associated it with the Latin word for "two.