A diva is a female performer, usually an opera singer, who is extremely talented but very imperious and tempermental. But the distinguishing factor is that her talent permits somewhat uncouth behaviour. A diva is not necessarily difficult to work with, she is just very professional and and has a low tolerance for incompetence. A diva is NOT just some no-talent pop singer who thinks everyone should acquiesce to her every whim, or even worse, some woman who is unecessarily rude, mean, bitchy, and often stupid just because she "knows what she wants" and revels in being high maitenance. These woman do not deserve the title of diva, because they have no redeeming talent or quality. They are simply loud and oboxious bitches. True divas should be treated with respect for their enormous talent and strong will.
Maria Callas was a quintessential diva, even being nicknamed "La Divina".
Kathleen Battle took her diva ways to new heights, and was subsequently banned from singing at the Metropolitan Opera.