It means, according to BabyCenter, "divine," and ranks at #180 for American baby girls in 2018.
This one is an obvious off-limits name. Princess Diana was adored by the public and of course, her two beloved sons, but the royal family had real issues with the mother of the heirs to the throne.
Diana seemed to break all the rules, much to the royals' chagrin and the
delight of the British people. She was once quoted saying: "I don't go by the rule book; I lead from the heart not the head."
She became the best-loved of all the monarchy, and when she and Charles divorced, he tried to get Camilla to be loved and admired, but it was a tough sell after Diana. When Diana died in 1996, her son William was 15, and Harry was just 12. William and Kate honored Diana with one of the middle names of daughter Charlotte Elizabeth Diana, which is why if this royal thirdborn had been a girl, her first name would not have been Diana. Diana is the Roman goddess of the hunt, childbirth and forests.
The mid-1940s was the heyday of this name, with 4800 Dianas per million babies in the US in 1946.