How Queen Elizabeth II Got the Nickname "Lilibet" as a Child

• Over the weekend, royal fans learned that Prince Harry and Meghan Markle have officially welcomed their second child.

• The Duke and Duchess of Sussex revealed that they named their daughter Lilibet "Lili" Diana Mountbatten-Windsor in honor of Queen Elizabeth and Harry's late mother, Princess Diana.

• "Lili is named after her great-grandmother, Her Majesty The Queen, whose family nickname is Lilibet," the couple explained of the unique first name in a statement announcing the birth. Here's what you need to know about the history of the Queen's childhood nickname.

Prince Harry and Meghan Markle delighted royal fans (and the rest of the royal family, FWIW) this weekend when they announced that they had welcomed their second child.

The Duke and Duchess of Sussex shared the news in a brief announcement on Sunday. Even though they didn't share any photos of the newest royal, Harry and Meghan did share a few key details about her, like her birthday (she was born on Friday, June 4), her weight (7 lbs 11 oz.) and, of course, her name: Lilibet "Lili" Diana Mountbatten-Windsor.

Harry and Meghan chose the unique name in honor of Queen Elizabeth II and Harry's late mother, Princess Diana. As the couple explained in the birth announcement, "Lili is named after her great-grandmother, Her Majesty The Queen, whose family nickname is Lilibet. Her middle name, Diana, was chosen to honor her beloved late grandmother, The Princess of Wales."

If you're not familiar with the Queen's adorable nickname, here's a little background.

How did Queen Elizabeth get her childhood nickname?

It's a well-known fact among royal fans that Lilibet was the Queen's childhood nickname, but not as many know the origin story behind the unique nickname. So, who bestowed the adorable moniker on the future monarch? Turns out it was Elizabeth herself. According to Hello! magazine, she wasn't able to pronounce "Elizabeth" when she was young, presumably pronouncing her own name "Lilibet," and well, the adorable error stuck.

Who called Queen Elizabeth "Lilibet"?

Growing up, the Queen's parents and grandparents called her Lilibet and her father, King George VI once famously said of her and her younger sister, Princess Margaret, "Lilibet is my pride. Margaret is my joy."

The nickname was one that the Queen embraced and Elizabeth was known to sign notes to loved ones "Lilibet."

"Darling Granny. Thank you very much for the lovely doll's house. I do love it, and I have unpacked the dining room and the hall. Love from Lilibet xxx," she wrote in a letter to Queen Mary written when she was a child.

Does Queen Elizabeth still go by Lilibet?

While this will always be one of the Queen's nicknames, that last known person to call the Queen Lilibet was her late husband, Prince Philip. In fact, the Queen reportedly signed the nickname to a note she laid on his casket at his funeral this spring.

Now, of course, the sweet nickname and it's adorable backstory and legacy will live on through her great-granddaughter, Lili.