What is the definition of the word "Diva"?

I just read the answers to this question, posed one year ago; and the answers seem to come from very young people who have little understanding of the word. A diva is/should only be used to describe a female opera singer. Divo, for a male. Urban dictionaries, including Wikipedia have a second definition to include younger female singers, i.e. Beyonce, Aretha, Cher, Celine Dion, Barbra Streisand, etc. None of these woman are true divas. Maria Callas was a diva, Angela Brown is a diva. The word has become misused and inaccurately applied to females undeserving of the title.