What is the difference between a duel and a dual?

Answer 1

"Duel" with an e is a noun meaning a match between two opponents. For example, Apple and Microsoft duel over market share of laptop computer sales.

"Dual" with an a is an adjective meaning two or paired. For example, my cousin purchased a truck with dual tail pipes.

Answer 2

1 affair of honour, single combat

2 clash, competition, contest, encounter, engagement, fight, head-to-head, rivalry

vb

3 clash, compete, contend, contest, fight, lock horns, rival, struggle, vie with

A prearranged combat with deadly weapons between two people following a formal procedure in the presence of seconds and traditionally fought until one party was wounded or killed, usually to settle a quarrel involving a point of honour

2 a contest or conflict between two persons or parties

3 to fight in a duel

4 to contest closely