You may call His Royal Highness...
"The Duke and Duchess of Cambridge are delighted to announce that they have named their son Louis Arthur Charles," Kensington Palace announced Friday. "The baby will be known as His Royal Highness Prince Louis of Cambridge."
Just days after welcoming their third child into the world on Monday, Prince William and Duchess of Cambridge Kate Middleton revealed their little boy's special moniker.
As for the baby's official title, according to royal historian Marlene Koenig who spoke to Town & Country, the little one will be called His Royal Highness Prince Louis of the United Kingdom of Great Britain and Northern Ireland. However, like his siblings and famous parents, little Louis will go by His Royal Highness Prince Louis of Cambridge.
Either way, that's quite a moniker to learn how to write on a name tag at school!
The tot joins big brother Prince George, 4, and older sister Princess Charlotte, 2. George's full name is George Alexander Louis, sharing George with Queen Elizabeth II's father, King George VI, and Louis with his father, whose full name is William Arthur Philip Louis.
Meanwhile, Charlotte's full name is Charlotte Elizabeth Diana. The choice of Charlotte was believed to be a nod to William's father Prince Charles and is also the middle name of Kate's sister Pippa Middleton and her grandmother Carole Middleton. Naturally, Elizabeth is a reference to William's grandmother and England's monarch as well as mom Kate's middle name. Diana, of course, is a tribute to Prince William's late mother.
Predicting the name of baby number three was all the more a challenge considering the couple did not know the sex of the baby until the birth.
Like his siblings and father, the Duke and Duchess' third bundle of joy was welcomed into the world in the Lindo Wing of St Mary's Hospital in London on Monday.
Queen Elizabeth's sixth great-grandchild is fifth in line to the throne, in front of Prince Harry and behind his brother and sister.