EXCLUSIVE

Kevin Durant is fighting back against a lawsuit claiming he stole the nickname "Durantula" from a 1980s musician ... arguing that he didn't give himself the moniker and doesn't even use it to make money.

As TMZ first reported, the Oklahoma City Thunder star was sued by guitarist Mark Durante, who claimed he had trademarked the name and used it to sell merchandise long before KD came along.

But in his response -- filed earlier this month in Illinois Federal Court -- Durant claims the media and his fans have been calling him by the name his whole career. Durant says he has NEVER used the name to sell merchandise ... so Durante's lawsuit has no merit.

In addition, Durant claims that no one would ever confuse him with Durante (who has played with the likes of Public Enemy, The Aliens and The Next Big Thing).

KD wants the lawsuit tossed completely and wants Durante to cover his legal fees.