Lili Chookasian, an American singer who in the 1960s and afterward was among the most prominent contraltos in the world, died on Tuesday, April 10, at her home in Branford, Conn. She was 90.

Her family confirmed the death, The New York Times reported.

Ms. Chookasian was a principal singer with the Metropolitan Opera for a quarter-century, appearing there 290 times from 1962 to 1986. She also sang in recital and was a soloist with many of the world’s leading orchestras.

Critics and operagoers hailed Ms. Chookasian as a “real contralto.” She was praised for her sensitive musicianship, powerful dramatic characterizations and impeccable diction. (She had grown up speaking Armenian.)

The daughter of Armenian immigrants, Lillian Phoebe Chookasian was born in Chicago on Aug. 1, 1921; her father was a machinist and toolmaker. A gifted singer from girlhood on, she made her professional debut in the 1940s as a soloist on the radio show “Hymns of All Churches,” broadcast nationally on the Columbia network.

Ms. Chookasian began her career as a concert singer, making a notable appearance in 1955 as a soloist in Mahler’s “Resurrection” Symphony with the Chicago Symphony under Bruno Walter. She made her operatic debut in 1959, as Adalgisa in Bellini’s “Norma” with the Arkansas State Opera and later studied with the distinguished soprano Rosa Ponselle.