“You have to know not only the time of day the scene is taking place, but also in which part of Italy it’s taking place,” he continued, “because in some places they start saying buona sera — ‘good evening’ — at 1 p.m. The minute they get up from the luncheon table it’s evening for them. So someone could say buona sera, but you can’t translate it as ‘good evening’ because the scene is taking place at 3 p.m. You need to know the language, but, even more, the life of the country.”

William Fense Weaver was born on July 24, 1923, probably in Washington, his nephew Mr. Poulton said; young William’s father, Henry, was a recording secretary for the House of Representatives. But the family also spent part of the year in Front Royal, Va., where William’s parents were from.

Mr. Weaver graduated from Princeton, though his time there was divided; after the attack on Pearl Harbor he joined the American Field Service, which sent him to Africa and then to Italy as an ambulance driver. He finished school after the war — as a senior, he had a short story published in Harper’s Bazaar — and then taught for a year at the University of Virginia before returning to Italy.

In Naples and then Rome, he fell in with a society of writers and artists and, in addition to writing himself, took up the study of opera. When a friend asked him to translate his novel, Mr. Weaver discovered his calling.

No immediate family members survive. Mr. Weaver’s partner, Kazuo Nakajima, died in May.

Mr. Weaver wrote often about opera, translating librettos by Verdi and writing, among other books, a history, “The Golden Century of Italian Opera From Rossini to Puccini,” and a biography of Eleonora Duse, the great Italian actress of the 19th and early 20th century. He wrote frequently about Italy in The New York Times, and was a guest commentator on radio broadcasts by the Metropolitan Opera.

Mr. Weaver liked to tell stories from the forefront of Italian literary life. In the interview with The Paris Review, he spoke of the novelist Elsa Morante, who was married to Alberto Moravia, as an insecure narcissist. He later translated her novel “History,” but in the early 1950s she was a dramatic, intimidating acquaintance who had just finished her first book, “House of Liars.”