WATCH VIDEO: Nicki Minaj BLASTS Mariah "You're a Bitter Old Woman!"

In case you forgot ... Nicki Minaj STILL HATES Mariah Carey ... and moments ago, she went after the diva AGAIN ... calling her a bitter old woman with no personality.

Minaj just unloaded on Twitter, following a series of heated exchanges on "American Idol" last night.  During the show, Mariah spit a little trash talk Nicki's way ... and taunted her for never having a #1 single on the Billboard Hot 100.

CLICK TO WATCH NICKI AND MARIAH