The name Diane is a girl's name of French origin meaning "divine". Diane and is often added to lists like Unique Vintage Names for Girls and discussed in our forums with posts like "Heaven / Hell / Purgatory Girls".
From the experts:
Like Joanne and Christine, middle-aged Diane has been overshadowed by the a-ending version of her name. Diane has a definite mid-century feel; it was a Top 20 name from 1946 to 1959. Though it has several distinguished bearers, including Dianes Sawyer, Keaton, von Furstenberg, Lane, Arbus, Kruger and Farr, it is rarely used for babies today.