The definition of what exactly constitutes a jazz singer is a perennial argument starter, and looking at vocalist Diane Schuur’s recent career, it’s easy to see why.

With two “Best Jazz Vocalist” Grammys under her belt and a three–decade track record working with the likes of Stan Getz and the Count Basie Orchestra, Schuur has made a name for herself as one of the most popular and forceful jazz singers on the scene (not to mention a hard-swinging pianist skilled at accompanying herself). But she’s as likely to croon a country ballad or explore the Barry Manilow songbook as she is standards by the likes of Gershwin, Arlen and Berlin. So where does that leave her? Is she a singer who primarily works in the jazz idiom or a jazz singer who pushes the envelope?

“I’ve always tried to stretch,” says Schuur, 53, who performs on Friday at the Golden State Theatre with her ace quartet featuring guitarist Dan Balmere, drummer Reggie Jackson and bassist Scott Steed. “I feel I’m a lot more than just a ‘jazz singer,’ but that’s the way some people think. In a way it narrows me, but that’s what I’ve been labeled all these years. In part that’s what I am, but that’s not all I am!”

Schuur’s first prominent exposure certainly came through her work with jazz musicians. In 1975, trumpeter Doc Severinson was in Seattle, auditioning singers for “Tonight Show” drummer Ed Shaughnessy’s upcoming appearance at the Monterey Jazz Festival. Schuur landed the gig and got her first big break, and Monterey was destined to play an important role in her career. At the 1979 Monterey Jazz Festival, legendary tenor saxophonist Stan Getz was blown away by her rendition of “Amazing Grace” and their blossoming friendship opened many doors for Schuur.

“It was a very significant musical relationship,” Schuur says. “Stan always stressed to me that less is more, that you should try to have more simplicity, and not be so busy in the delivery of a song. And I was very grateful he was able to take me to the White House in 1982, and we did Carnegie Hall together in ‘86.”

It was during a performance at the White House in 1984, broadcast on PBS, that GRP co-founder Larry Rosen heard Schuur and was impressed enough to sign her to the label. After her first GRP release, 1985’s >>Deedles (the moniker with which she always refers to herself), Schuur recorded a dozen albums for GRP, and demonstrated an ability to tackle many different kinds of material.

Since signing with Concord in the late 1990s, Schuur has continued her eclectic ways. On 2000’s >>Friends for Schuur, she teamed up with stars such as Stevie Wonder, Ray Charles, Stephen Bishop and Herbie Hancock. The following year, she put her pipes to the test with the Maynard Ferguson Big Bop Nouveau band on >>Swingin’ For Schuur. She took a refreshing, tropical turn with the Caribbean Jazz Project on 2005’s >>Schuur Fire, but on her latest album, >>Live in London, she sounds a little ragged (and seems to have exhausted the puns on her last name).

The album does showcase her keyboard skill as she tears through her trademark opener “Deedles’ Blues,” waxes sensitive on “Poinciana” and lays down a propulsive Latin groove on “Besame Mucho.” Over the years she’s hired some of the greatest jazz musicians in the world to accompany her, but like the late Shirley Horn, Schuur is never happier than when she’s in the driver’s seat.

“When I have other people working with me, they’re some really good players, but they have a hard time with comping, because they’re into their own trip,” Schuur says. “When I’m at the piano doing my own thing, I have control over it.”

Born in Tacoma, Washington and raised just outside of Seattle, Schuur was drawn to jazz at an early age. Exposed to the music of Duke Ellington and other jazz musicians by her mother and the rudiments of the piano by her father, she quickly realized that she had a musical calling.

“I’ve always known that I wanted to be a singer, ever since I was practically pre-verbal,” Schuur says. “I wasn’t sure about making a living all those years, but I started professionally when I was 9 years old and I’ve been making a living at it ever since.”

Making a living is an understated way of describing Schuur’s enduring career, particularly considering how close she came to becoming a show business cliché. Compulsive eating, drugs and alcohol began to take their toll on Schuur during her first burst of notoriety, and by the late 1980s she decided to make some major changes in her life. She’s gone from strength to strength since then, and she shows no signs of slowing down.

“I just got tired of feeling sick and tired,” Schuur says. “I hit my bottom with alcohol in 1989 and with the drugs earlier on, and the overeating about January of ‘88, that’s when I started the diet. I just wanted to feel better about myself. I wanted to stay alive and I knew if I kept on the course that I was on, then there would have been no way I would have lived much longer.”  

DIANE SCHUUR plays the Golden State Theatre, 417 Alvarado St., at 8pm on Friday, Dec. 15. $29-$39, 372-4555 or goldenstatetheatre.com