Bill Cosby's effort to get his sexual assault conviction overturned has been denied ... because the appellate court wasn't buying what he tried to sell.

According to new legal docs ... Cosby's claims about unfair testimony in the Andrea Constand case were ruled invalid. Cosby felt the testimony from 5 other women was bogus because their allegations were more than 15 years old, and too different from Constand's allegations.

The appellate court ruled the testimony from the women was warranted because it established Cosby's "unique sexual assault playbook" ... and spells out exactly what it was.

According to the docs ... Cosby would target women substantially younger than him, invite them to hang out, get them to trust him because of his celebrity status, ply them with intoxicants and then sexually assault them while they were not fully conscious.

The appellate court ruled the trial court in Cosby's case did nothing wrong, and the testimony established the disgraced comedian's predictable pattern of behavior.

The court also rejected additional arguments by Cosby, including his long-held stance that he had a deal with the D.A. not to prosecute him.

As we've reported ... 82-year-old Cosby was sentenced to 3 to 10 years for sexually assaulting Constand at his home his 2004.

If he appeals again ... it'll go to the Pennsylvania Supreme Court.