The four-letter crossword solution for the term 'FAMOUS OPERA' is AIDA. AIDA is an opera composed by Giuseppe Verdi in 1871. It is based on a story set in ancient Egypt and follows the love triangle between AIDA, an Ethiopian princess, Radames, an Egyptian soldier, and Amneris, the daughter of the King of Egypt. It is one of the most popular operas of all time and has been performed in many countries around the world.