Adrian Peterson -- Appeal of Suspension DENIED

Adrian Peterson has almost ZERO chance of getting back on the field this season -- the NFL star's appeal of his suspension was denied Friday.

Peterson was immediately placed on leave after his arrest for abusing his 4-year-old son. The case wrapped up on Nov. 4 .. when he pleaded no contest to misdemeanor reckless assault. He had hoped the NFL would reinstate him shortly after that.

No dice. Instead the Vikings running back was suspended without pay. He appealed the NFL ruling, but an independent arbitrator ruled today the punishment was fair and consistent ... and refused to lift the suspension.

Peterson plans to appeal the ruling in federal court, but with only 3 Sundays left in the regular season ... it's highly unlikely he'll be back in 2014.

Ray Rice got his suspension overturned back on Nov. 28 -- but still hasn't been signed by an NFL team.