Prince William and Kate Middleton name the royal baby Louis

Prince William and Kate, the Duke and Duchess of Cambridge, have named their third child Prince Louis Arthur Charles of Cambridge, Kensington Palace announced Friday.

The baby will be known as His Royal Highness Prince Louis Arthur Charles.

The pair welcomed their third child on Monday, which was also St. George's Day, the feast day of Saint George, a patron saint.

The name pays tribute twice over to Prince Charles, who has Arthur as one of his middle names.

The choice also honors Louis Mountbatten, Charles' great-uncle and beloved mentor, who was killed by an Irish Republican Army bomb in 1979.

Louis — pronounced LOO-ee — is fifth in line to the throne after his grandfather Prince Charles, his father and his older siblings, Prince George and Princess Charlotte.

Charlotte has become the "first-ever member of the royal family that will not lose her spot in line to the throne if a male heir is born," thanks to the Succession to the Crown Act passed in 2013 makes this possible.

The name pays tribute twice over to Prince Charles, who has Arthur as one of his middle names.

Prince Louis' birth pushed William's brother, Harry, to sixth in line for the throne. Prince Harry is set to marry American actress Meghan Markle on May 19.

Bookmakers had been doing a brisk trade in bets on the new prince's name, but Louis wasn't among the favorites. The royal couple has used it before, as one of George's middle names.

Arthur, Albert and James had been considered front-runners.

Fox News' Jennifer Earl and The Associated Press contributed to this report.