Spar has two main meanings:

1. To practice fighting or boxing with a partner, usually with controlled punches and defensive moves. Boxers spar in the gym to improve their skills without actually trying to hurt each other. They wear protective gear and follow rules, learning how to anticipate moves, defend themselves, and find openings for their own strikes. Friends might spar playfully, trading light, harmless punches while joking around. The word can also describe verbal arguments: when two debaters spar over an issue, they're trading opposing views back and forth, each trying to score points with clever arguments.
2. A strong wooden or metal pole used to support sails on a ship. The masts, booms, and yards that hold up a sailing ship's sails are all types of spars. These poles must be incredibly strong because they bear enormous force when wind fills the sails. Sailors in the age of sail needed to climb these spars high above the deck to adjust rigging and sails, which required both courage and skill. A ship with broken spars couldn't sail properly, leaving it helpless at sea.