There is something about the word comeback that has slightly sinister overtones. Too often it implies an artist attempting to revive a reputation that's been in a slump. Sometimes it simply denotes a return to activity after a voluntary withdrawal.

The return of Miles Davis at New York's Kool Jazz Festival last night, the most anxiously awaited event in the world of jazz, is neither of these. The godfather of the trumpet and fluegelhorn played his last public notes in the spring of 1975. His absence since then was due to more than half a decade of intermittent illnesses. Inquiries about his health usually drew an evasive response or were impatiently brushed aside.

Year after year, Davis had maintained a public image as the hostile audience-hater, the monosyllabic prince of darkness, a cryptic figure who intimidates strangers and confines himself to reclusive living among a coterie of cronies. While this posture has drawn a commercially valuable veil of mystery around him, the real Miles Davis is warm, unsparingly honest and deeply loyal to old friends.

He is still not a well man. During our latest long-distance phone conversation, the second in recent months, he was in pain from time to time; his leg was being massaged as we spoke.

The last time we had talked, in March, Davis had been in no condition to go back to work. "How've I been?" he echoed my opening question. "You know how I've been -- I've been screwed up for five years. They split my leg down the middle, you know." (According to Teo Macero, Davis' record producer, he may well have been in danger of losing the leg. When an infection developed, an incision had to be made from the kneecap to the hip.)

How many operations has he had? "Three. The hip twice, the thigh. I still have trouble walking, especially when it gets cold. But otherwise, I'm doing all right; still weigh about 141, that's about normal for me; but I'm going to the gym next week."

He had started to work on an album for CBS, but "I haven't been able to finish it; I had to go in the hospital. I can't stand up and play with my leg in this condition."

But soon Davis was going into the studios every day and getting his chops into firmer shape than ever. His technical capabilities fully returned, the album was completed.

The logical follow-up was a return to the public eye. Last night he gave two concerts at Avery Fisher Hall at the Kool Jazz Festival (formerly the Newport Jazz Festival). Both concerts were sold out.

Recently we talked again, though the phone call was 10 percent words and 90 percent music. Davis could hardly wait to play me the entire album, and as the sounds wafted over long distance, they were punctuated by his guttural, barely audible whisper: "You hear that? . . . What did you think of that? . . . How d'you like that?"

The sounds were somehow different from the heavy funk of his last album (1974). Asked whether he feels he has changed, he said, "I just play more chords. And it's all acoustic horn, nothing amplified except for one track."

A soprano sex floated through. "Who's that?" "Bill Evans. I asked Dave Liebman, who used to play tenor with me, to find me a sax player and he recommended Bill. He's young, about 22, and he's a b----."

The rhythml section seemed different. Davis explained: "I didn't use any keyboard. Just Mike Stern on guitar; another guitarist, Barry Finnerty, on some tracks. I had Al Foster on drums, Sammy Figueroa on percussion, and Nino, a conga player from Martinique.

"Listen to this number. You hear that rhythm? That's bossa nova and calypso mixed. You like that? . . . You know I found out if you don't have nothing to say, just let the rhythm section play.

"listen to this part now -- the way I use volume for contrast highs and lows; build up and then come way down . . . Hey, my leg is hurting bad -- it just started to hurt all over -- no warning, nothing. Hold the line a minute."

Silence. Then more music. A vocal. "That's the title number of the album, 'The Man With the Horn.' The singer's Randy Hall. We brought him in from Chicago."

"Is this the same band you're going to have at the festival?"

"Same band."

"How about some other dates? After five years, people must be screaming to hear you in Europe, screaming for you in Japan."

"Well, if I get the money, I'll go." (Producer George Wein says he is paying Davis, for the two New York concerts, "more money than I ever paid anybody.")

"How long did it take you get back in playing shape?"

"Are you kidding? I just picked up the horn and started playing. How do you forget something like that? I've been playing since I was 12." (Macero confirmed that Davis took remarkably little time to restore full command of his strength and sound.)

Since he was not much more than 12, Miles Dewey Davis has been one of the true mavericks of contemporary music. The son of a wealthy dentist and landowner in East St. Louis, Ill., he was sent to New York by his father ostensibly to go to music school, but soon learned more of what he wanted from hanging out with Charlie Parker than he could absorb at Juilliard. He revolutionized jazz with his "Birth of the Cool" sessions, marking the first transition from be-bop, in 1949 and 1950. Seven years later he began the crystalline collaborations with arranger Gil Evans, creating three albums that are still unsurpassed: "Sketches of Spain," "Miles Ahead" and "porgy and Bess." During this period he also led a small group with John Coltrane, Cannonball Aderley and Bill Evans.

The 1960s found him advancing small-combo music through modal and, later, electronic experiments, mainly with the quintet: Wayne Shorter, Herbie Hancock, Ron Carter, Tony Williams. In 1969 the jazz world went into rock-shock when he recorded "Bitches Brew," an unprecedented melange of multiple keyboards, bass clarinet, John McLaughlin's electric guitar, drums and percussion. As always, the audience took sides, but the sales figures were on Davis' side. He became the first truly commercial jazz superstar, remaining at or near the top until illness struck him down.

Some skeptics have observed that for all his accomplishments in the funk/rock realm, he could not play today with the simple, lyrical beauty that marked his Gil Evans collaborations. Yet there is reason to believe he could go in any direction his inclinations might guide him. Only recently, as if to mark his return to the world, he strolled into the Village Vanguard where the Mel Lewis big band was playing its regular Monday night gig.

"I just sat in and played everybody's horn," he said. "Tried out all the trumpets."

"Did you play all the parts?"

"I played my part."

"Out of sight! The brass section's better than ever."

In another rare public appearance, he visited the new Savoy Club in midtown Manhattan during a one-night stand by Carlos Santana, whose band honored the unexpected guest by playing the theme from Rodrigo's "Concierto de Aranguez," which Davis recorded in 1950 as part of "Sketches of Spain."

Aside from such occasional ventures he has spent most of these years of alternating illness and recuperation holed up in his spacious brownstone on Manhattan's Upper West Side. He bought the building about 20 years ago and lives there in a life style that steems from years on the charts, composer royalties dating back more than three decades and wise stock investments. His retirement could not have been a matter of economic hardship any more than his retirement is dictated by financial necessity.

"Has Gil been in touch with you?"

"Gil's always my main man. You known, his son's name is Miles, and he comes by here to talk about trumpet. He's about 18."

"How about your own children?"

Davis chuckled and answered kiddingly: "I don't know. Probably in jail. No, my daughter makes a lot of money, teaching school in East St. Louis."

"How many grandchildren do you have?"

"About six."

"When will the album be out?"

"Very soon. You know, they got 300,000 advance sales already. CBS gave me a Yamaha grand for my birthday."

A moment's silence, then: "Here's a ballad for you." The tune that followed was presumably "Ursula," since I had already listened to "Fat Time," "Back Seat Baby," "Shout," "Aida" and the album's title tune.

I was asked how I liked it. It sounded fine.

"Good. I wrote four of the tunes, you know . . . Now write something nice about me."

As I was about to say goodbye, Miles got in an important postscript under the wire:

"I bought me a brand-new Ferrari. A yellow one."

Miles Davis is back, in love with life and music and women and Ferraris, not necessarily in that order. Given the length of his absence and the immense loyalty of his admirers, it would seem the reaction when he faced the New York audience last night would have imposed a severe test on the foundations of Avery Fisher Hall.