Uranus, unlike Pluto, had no designation prior to its discovery because it was never predicted: this differs from Neptune and Pluto, the former of which was called LeVerrier's Planet, the latter of which was called Planet X prior to discovery.
Uranus was originally called The Georgian Star, or Georgium Sidus: William Herschel discovered the planet Uranus in 1781. This was a major discovery because it was the first planet to be discovered after the known planets (Mercury, Venus, Mars, Saturn and Jupiter), all of which were known since prehistoric humans. Herschel was ethnically German, as were the Hanoverian dynasty in England, and Herschel named the planet the Georgium Sidus, or Georgian Star, after King George III. This reflected Galileo's choice for the Moons of Jupiter, which he called the Medicean Planets.
Johann Elert Bode suggested Uranus in 1782, but it was not adopted until the mid-19th century. It is curious that another astronomer, Erik Prosperin, suggested Neptune, which of course was applied to another planet discovered in 1846.