With her slow, meditative ballads, Horn was one of the leading jazz singers of her generation and unquestionably was Washington's preeminent jazz musician. After reviving her dormant career in the 1980s, she made a series of triumphant concert appearances and strong-selling recordings that earned nine Grammy nominations. Her performances at the White House in 1994 and at New York's Lincoln Center in 1998 were broadcast nationally on PBS.

An uncompromising perfectionist, she worked hard to develop a personal, pensive sound. Her artistry had long depended on the interaction between voice and piano, but in 2001, Horn's right foot was amputated because of her diabetes. As a result, it was difficult for her to use the elegant pedal work that marked her piano style.

Later, she would sometimes remove the shoe from her prosthetic foot and manipulate the piano's sustain pedal with the force of her hip. In her final public appearance, in December at the Kennedy Center, she climbed from her wheelchair to the piano and performed what had become her signature song, "Here's to Life."

Horn was a piano virtuoso as a child, focusing initially on classical training until she discovered the music of Erroll Garner and other jazz pianists. Her first jazz record, in 1960, was on a minor label, and she remained forever mystified about how trumpeter Miles Davis found a copy. He appreciated the lingering silences of her music, similar to his own style at the time.

In later years, Horn won legions of listeners with her exaggeratedly slow, intimate ballads in which her words seemed to melt in the air.

"I've never known anyone that could do a ballad that slowly and keep it musical, keep it happening," pianist Marian McPartland told Down Beat magazine. Horn was a strong influence on many younger singers, including jazz pianist-vocalist Diana Krall.

Davis's early advocacy of Horn's work led to a wider introduction to the New York jazz world and enabled her to meet producer Quincy Jones. When her albums for Jones misfired -- she was frustrated to be cast as a stand-up singer -- she found herself without a contract and back in Washington as jazz was fast losing ground to rock and other pop sounds.

She performed when possible but settled primarily into a life as a wife and mother, demurring from some festival dates that might have given her greater exposure.

In 1980, while attending a musicians' convention in Washington's Shoreham Hotel, she sat down at the piano sometime after midnight one night with some old friends. The performance apparently dazzled many in the crowd, including recording executives and concert promoters.

She then accepted an invitation to the North Sea Jazz Festival in the Netherlands, and her mesmerizing concert led to a career resurgence. She received a contract with the prestigious Verve record label and was championed by leading jazz critics.

Her reborn career culminated in a Grammy for best jazz vocal performance in 1998 for "I Remember Miles," a tribute to her former mentor. The album cover featured an illustration Davis had made of them years earlier.