Mel Torme, the fluent pop-jazz singer who earned the nickname the Velvet Fog for his smooth, soft vocal timbre, died yesterday of complications from a stroke he suffered in 1996. He was 73 and lived in Beverly Hills, Calif. Mr. Torme was rushed early yesterday from his home to the University of California at Los Angeles Medical Center, said his publicist, Rob Wilcox.

A supreme vocal technician whose style encompassed everything from intimate pop crooning to jet-propelled scat improvisations, Mr. Torme was rivaled in virtuosity only by Ella Fitzgerald, who moved between the worlds of pop and jazz with a similar ease. An innate classicist who approached popular songs with an analytic sense of balance and proportion, Mr. Torme infused everything he sang with a geniality that seemed ingrained in a voice that was incapable of making an unpleasant sound.

Mr. Torme was also a prolific songwriter, drummer, pianist, musical arranger, actor and author. His most famous composition, ''The Christmas Song'' (also known as ''Chestnuts Roasting on an Open Fire''), written with the lyricist Robert Wells, became one of the most beloved of seasonal standards after it was recorded by Nat (King) Cole in 1946.

Mr. Torme liked to recall that the song was written in just 40 minutes on a sweltering July afternoon in Los Angeles and that it had subsequently been recorded in 1,734 versions.

The singer's several books included ''The Other Side of the Rainbow'' (1970), an account of his experiences as the musical adviser to Judy Garland on her television shows in the 1960's, a novel, ''Wynner'' (1978), and an autobiography, ''It Wasn't All Velvet'' (1988). The Garland book, with its portrait of the troubled singer, won critical praise but earned the wrath of her family, who unsuccessfully sued Mr. Torme.

But it was as a singer that Mr. Torme made his deepest mark. The critic Will Friedwald, in his book ''Jazz Singing,'' cited Mr. Torme as a pioneer of ''cool jazz,'' spun off from the pop crooning of the day.

''Torme works with the most beautiful voice a man is allowed to have, and he combines it with a flawless sense of pitch,'' Mr. Friedwald wrote. ''As an improviser he shames all but two or three other scat singers and quite a few horn players as well.''

His standards included ''Blue Moon,'' ''It Might as Well Be Spring,'' ''Oh, You Beautiful Doll'' and ''Mountain Greenery.''

He received a lifetime achievement award from the National Academy of Recording Arts and Sciences at February's Grammy Awards.

Melvin Howard Torme was born on the South Side of Chicago on Sept. 13, 1925, to a working-class Jewish family. His parents were immigrants whose name had been changed from Torma to Torme by an immigration agent. He was a musical prodigy who sang professionally at age 4 with the Coon-Sanders Orchestra, singing ''You're Driving Me Crazy,'' at the Blackhawk restaurant in Chicago for $15 a session, and he was a busy child actor on radio serials, appearing from 1933 to 1941 on such network programs as ''The Romance of Helen Trent'' and ''Jack Armstrong, the All-American Boy.'' As an adult, he was nominated for a best supporting actor Emmy in 1956 for a role in ''The Comedian,'' a Playhouse 90 production.

He started writing songs at 13 and was only 16 when Harry James scored a hit with his song ''Lament to Love.'' While still a teen-ager, he toured as a singer, arranger and drummer in a band led by Chico Marx of the Marx Brothers.

In 1943, he made his movie debut in the musical ''Higher and Higher,'' playing a supporting role to Frank Sinatra, who was also making his film debut.

The same year he formed Mel Torme and His Mel-Tones, whosang in the style of Frank Sinatra and the Pied Pipers. After his appearance in the 1947 musical ''Good News'' made Mr. Torme a bobby-soxer idol, the Mel-Tones slipped increasingly into the background.

He was only 21 when he appeared as a soloist at the Copacabana in New York, and Fred Robbins, a local disk jockey, gave him the nickname Velvet Fog, a sobriquet he detested. Mr. Torme recorded for Decca in 1945, for Musicraft (1946-48), singing with the Artie Shaw Orchestra, and in 1949 moved to Capitol, where his first recording for the label, ''Careless Hands,'' was his only No. 1 hit. It was followed by a two-sided hit, ''Again'' and ''Blue Moon,'' one of his best-loved signature songs. The same year, his composition ''California Suite,'' a jazzier answer to Gordon Jenkins's pop oratorio ''Manhattan Tower,'' became the label's first 12-inch LP.

Mr. Torme was 30 when he met Red Clyde, the jazz producer who founded Bethlehem Records, and decided to switch gears and move toward jazz. From 1955 to 1957, he recorded seven albums for the label, including ''Mel Torme With the Marty Paich Dektette,'' a pop jazz classic featuring a 10-member ensemble (arranged by Mr. Paich) that combined the power of a big band with the freedom of a small ensemble.

''I wanted to embed in the minds of the public at large, particularly jazz fans, that this syrupy, creamy bobby-sox sensation was taking the musical bull by the horns and singing the kind of music he wanted to sing,'' Mr. Torme later recalled.

But artistic integrity did not breed commercial success.

''I can't deny that I would have been pleased to have a best-seller,'' Mr. Torme said, ''but if you're constantly working to good rooms and to good crowds, records are only frosting on the cake. Yet my managers kept bugging me for the big hit, and to satisfy them, when rock erupted in the mid-1960's, I recorded some of the worst dreck you can imagine -- to no avail.''

Soon Mr. Torme found himself eking out a living playing out-of-the-way clubs. As rock-and-roll solidified its domination of the airwaves, he briefly considered retiring from music and becoming an airline pilot.

The next two decades were a frustrating period of dues-paying in which Mr. Torme moved from record company to record company and often found himself forced to record the pop hits of the day with tinny arrangements. He managed to score a minor hit, with a blues song, ''Comin' Home, Baby,'' in 1962.

His reputation as a jazz singer continued to grow, based on his live performances. In 1976 he won an Edison Award (the Dutch equivalent of the Grammy) for best male singer, and a Downbeat award for best male jazz singer.

The ground swell of recognition accelerated after a triumphant 1977 Carnegie Hall concert with George Shearing and Gerry Mulligan, which Mr. Torme viewed as a turning point in his career. He later recorded five albums with Mr. Shearing, whose cool, romantic pianism perfectly complimented Mr. Torme's serene vocal style.

''It is impossible to imagine a more compatible musical partner,'' Mr. Shearing said after hearing of Mr. Torme's death. ''I humbly put forth that Mel and I had the best musical marriage in many a year. We literally breathed together during our countless performances. As Mel put it, we were two bodies of one musical mind.''

In 1982, Mr. Torme finally found a stable recording base in Concord Jazz Records, for whom he made a succession of albums that established him as an articulate custodian of a broad pop-jazz-swing tradition that encompassed Bing Crosby, Fred Astaire, Duke Ellington, Benny Goodman and the Gershwins.

Mr. Torme's career also got a lift in the 1980's through the television series ''Night Court,'' in which Harry Anderson's character, Judge Harry Stone, was an unabashed fan.

Mr. Torme was married four times. His first three marriages ended in divorce. He is survived by his wife, Ali; five children, Steve, Melissa, Tracy, Daisy and James Torme, all of Los Angeles, and two stepchildren, Carrie Torme and Kurt Goldsmith.

Regular appearances at the JVC Jazz Festival and annual nightclub engagements at Michael's Pub in Manhattan solidified Mr. Torme's position as a musician who melded the achievements of the past into a sweeping but personalized vision of American popular music in its golden age as a vernacular kind of classical music.

For well over a decade, Mr. Torme's September appearances at Michael's Pub unofficially opened New York's fall cabaret season. A typical Torme performance there might have been a salute to a pop music giant like Bing Crosby, Fred Astaire or Benny Goodman, in which the singer distilled his rich personal vision of a career in less than an hour.

These shows featured intricate medleys that showcased Mr. Torme's phenomenal flexibility as both a singer and an arranger with an enthusiasm for his subject that matched his encyclopedic knowledge. Such a medley might string fragments from as many as two dozen songs into a virtuosic vocal (and sometimes also drum) display that would change in mood every few seconds as the singer glided from the most ethereal pop crooning into the sort of machine-gun driven scat improvisations that only Ella Fitzgerald, in her prime, could match in precision and rhythmic intensity.

These engagements compressed volumes worth of pop-jazz history and lore into an explosion of musical energy that was as lucid as it was comprehensive.

''I do not believe there's such a thing as a jazz singer,'' Mr. Torme declared late in his career.

''Every pop singer is influenced a little by jazz, because it's our native folk art,'' he said. ''But labeling someone a jazz, rather than a pop singer, is only a matter of degree of influence.''

Selective Discography

''Mel Torme Sings Shubert Alley'' (Verve). A light, swinging collection of show tunes recorded in 1960 with the Paich Dektette includes sizzling renditions of ''Too Darn Hot'' and ''Just in Time,'' and a melting version of ''A Sleepin' Bee.''

''Mel Torme: A Tribute to Bing Crosby'' (Concord Jazz). Recorded with a 20-piece string orchestra, this 16-song collection features smooth-as-silk versions of Mr. Crosby's movie songs.

''The Mel Torme Collection'' (Rhino). The collection of four compact discs includes 92 songs recorded between 1944 and 1985, when Mr. Torme signed with the Concord Jazz label. All the early hits are here, as well as the best of the Dektette years.

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