Prince William, Kate Middleton, Meghan Markle and Prince Harry show their love in small but sweet ways, one of which is by calling their respective partner by a special nickname or term of endearment.

Prince Harry and Meghan Markle, who are getting married on May 19 at St. George's Chapel at Windsor Castle, have nicknames for each other. According to Gina Nelthorpe-Crowne, the "Suits" star affectionately calls her groom-to-be "Haz."

Prince William, meanwhile, reportedly calls his wife "darling" or "poppet." Duchess Kate Middleton doesn't have a shortened nickname for her husband, but was heard calling the Duke "babe."

When Prince William and Middleton attended the Chelsea Flower Show back in 2016, the couple had been looking at the prize-winning garden cultivated by Charlie Albone when Prince William asked the Australian landscaper about the plants, which he called Buxus shrubs. According to Albone, the Duchess replied to her husband and said, "Babe, we've got those. We've got loads of those."

Meanwhile, Prince Charles and Camilla Parker-Bowles apparently call each other "Fred" and "Gladys." In fact, Princess Diana was reportedly furious after discovering a gold chain bracelet with a blue enamel disc that the Prince of Wales had made for Camilla as a parting token before he married the People's Princess.

The bracelet was engraved with an entwined "G" and "F," which stands for their pet names. Princess Diana reportedly confronted Prince Charles about it. However, he went ahead and presented it to the Duchess of Cornwall two days before he exchanged "I do's" with the late Princess of Wales.

Prince Charles was also heard referring to Camilla as "mehbooba" at the British Asian Trust dinner at the Natural History Museum in London. The nickname is a Hindi term that means "beloved."

On the other hand, Queen Elizabeth II was known as "Lilibet" when she was a child. Prince Philip also called her that way, but after seven decades of marriage, the Duke of Edinburgh has learned to call Her Majesty "cabbage."

In related news, Prince George and Princess Charlotte call the monarch "Gan-Gan." According to Middleton, the queen is a sweet and thoughtful great-grandmother.

"She always leaves a little gift or something in their room when we go and stay, and that just shows her love for the family," the Duchess of Cambridge said.

It remains unknown how the 4-year-old little prince and the 2-year-old princess address Camilla. However, Camilla said in an interview earlier that she wanted the kids to refer to her as "GaGa" because it's how her grandchildren call her.