Rosa Melba Ponselle was an opera singer with a powerful voice and a prolific career. To describe her, one could use synonyms such as talented, accomplished, gifted, skilled, and expert. She was also known for her beauty, so words like stunning, attractive, and elegant could also be used. In addition, Ponselle was well-regarded by critics and audiences alike, so words like esteemed, celebrated, and revered could be applied to her. Overall, Rosa Melba Ponselle was a multifaceted artist who left a lasting impact on the opera world, and any number of positive descriptive words could be used to capture her essence.