Final answer:
The nickname "Old Ironsides" refers to the USS Constitution, a famed American frigate constructed from American oak. It became a symbol of American naval prowess during the blockades imposed by the British, and earned its nickname during an encounter where a cannonball bounced off its hull.
Step-by-step explanation:
The ship that earned the nickname "Old Ironsides" is the USS Constitution. This historic vessel was a centerpiece of the American fleet during the time when the British had imposed a blockade on American ports. Despite the Americans not having enough ships to break the blockade, the USS Constitution, known for its solid construction of American oak, achieved naval victories that boosted American morale. One particularly notable incident involved the USS Constitution under Captain Isaac Hull evading a group of British ships for fifty-seven hours, showcasing its impressive speed. Furthermore, the nickname "Old Ironsides" was bestowed upon the ship during a battle with the British frigate Guerriere, when a cannonball fired at the Constitution miraculously bounced off its sides, as if they were made of iron, rather than timber.