duel

The story

1. Middle French · derived fromduel
2. Old Latin · derived fromduellum“war, fight”
3. Medieval Latin · derived fromduellum“fight between two men, duel”
4. English todayduel

From Medieval Latin duellum (“fight between two men, duel”), itself from Old Latin duellum (“war, fight”), which survived in Classical Latin as a rare byform of bellum and was later reinterpreted as “duel” by unetymological association with duo (“two”). May have entered English through Middle French duel.