The term 'Queen of the Opera' is often used to refer to a female opera singer who has achieved great success and fame. The two crossword solutions for this term are 'DIVA' (4 letters) and 'primadonna' (10 letters). A DIVA is a female singer who is highly acclaimed for her singing ability and stage presence. A primadonna is an Italian term for a female opera singer who is considered to be the star of the show. Both terms are used to describe a female opera singer who is highly respected and admired.