Turner was voted off the Fox show after singing Crystal Gayle's "When I Dream," a choice that the judges lambasted.
"It was an appalling choice of song and I think you could go home after that," said judge Simon Cowell, adding that it was the musical equivalent of wallpaper.
The judges, who rarely find themselves in agreement, were unanimous in their appraisal of the odd selection, which went with the show's theme of tunes from the year each contestant was born.
"A year's worth of songs and you chose that one," said judge Randy Jackson of the 1977 song.
Turner defended the choice: "It's a song about dreaming and I've always been a dreamer."
It was a disheartening turnaround for the 28-year-old Miami native, who Cowell earlier described as a "steak" among "a competition full of hamburgers."
The elimination of Turner, a bartender and waitress and member of a rock-soul Christian band, narrowed the Idols to seven.
Just barely surviving were Scott Savol and Bo Bice, a long-haired rocker who performed "Free Bird" Tuesday. Bice has frequently been cited as a favorite in the competition, but was in the bottom three of vote-getters Wednesday.
Savol had performed Hall and Oates' "She's Gone" and bristled at Cowell's criticism that his performance was full of "bum notes."
"I'm up here and there's, like, millions of people at home who didn't have the nerve to do this," Savol said.
The Wednesday night episode was extended to an hour, leaving host Ryan Seacrest with a lot of time to fill.
"I'm definitely going to earn my money tonight as I host a results show stretched out further than Kirstie Alley's cycling shorts," said Seacrest.
Seacrest also announced that a single sung by the top 12 contestants had been chosen. "When You Tell Me that You Love Me" will be released April 19, with benefits going to the American Red Cross.
The "American Idol" finale is scheduled for May 24-25.