Daniel Cormier -- Jon Jones Is a Drug Addict

Daniel Cormier took things personal with Jon Jones Wednesday morning -- calling him a drug addict to his face ... and threatening to "beat that ass" at UFC 200.

Cormier was responding to Jones -- who had asked Daniel what he'll say to his kids if they ever ask, "Daddy, did you ever beat Jon 'Bones' Jones?"

Cormier essentially said he didn't HAVE to beat Jones to get his championship belt because Jones eliminated himself by testing positive for cocaine.

FYI -- Jones has said he's NOT an addict ... but admits he made a "really dumb decision" before the drug test for UFC 182 last year.

The back-and-forth between these guys is nasty ... and multiple people in the UFC tell us the hatred is 100% legit.