Paul Plishka, an American singer acclaimed for his sonorous, liquid bass tones and near-perfect diction during a career at the Metropolitan Opera that spanned a half-century, died on Monday in Wilmington, N.C. He was 83.

His death was confirmed by his wife, Sharon Thomas, who did not cite a cause or specify where in Wilmington he died.

Known for a disciplined approach to choosing roles and a great concern for the development of his voice, Mr. Plishka was one of the most prolific solo singers at the Met, where he appeared in 88 roles over 1,672 performances.

“I think the secret of my longevity was having the good sense to turn down repertoire that wasn’t right for my voice at the time,” he said in an interview for this obituary in 2023.

Early in his career he preferred buffo, or comic, roles, especially in operas by Verdi. “My voice was more of the basso cantante — with a lyric kind of sound — not a villain’s voice,” he said.

But as his voice changed, Mr. Plishka accepted more dramatic roles, including the title one in Mussorgsky’s “Boris Godunov,” as Philip II of Spain in Verdi’s “Don Carlos” and as Mephistopheles in Gounod’s “Faust” — all stellar performances.