Polly Lauder Tunney, a Connecticut socialite and Carnegie heiress whose secret romance and subsequent marriage to the former heavyweight champion Gene Tunney was one of the most sensational love stories of the 1920s, died Saturday at her home in Stamford, Conn. She was 100.

Her death was confirmed Monday by her son John V. Tunney, the former United States Senator from California. His mother had had several strokes in recent years, including one about a week ago, he said.

For Mrs. Tunney, who had grown up in a world of wealth and privilege reaching from Greenwich, Conn., to Versailles, meeting and falling in love with a prizefighter, even a famous one, seemed unlikely. But Gene Tunney was no ordinary prizefighter.

Though he had grown up relatively poor in Greenwich Village as the son of Irish immigrants — his father was a longshoreman — Tunney, a high school dropout, had developed an insatiable appetite for classical literature, especially the works of Shakespeare. Handsome and articulate, he lectured on Shakespeare at Yale and befriended George Bernard Shaw, Thornton Wilder and other writers, earning the scorn of the boxing establishment and many boxing fans.