Ciara: Baby Future Calls Russell Wilson ... 'Papa'?!!

Future's worst nightmare just became REALLY real -- his son, baby Future, is calling Russell Wilson ... "Papa," and it seems like a regular thing.

Ciara and Russell posted a video on Facebook Live as Russ seemed to be prepping for a TV appearance -- and baby Future was brought in the room to give a "mama kiss." No biggie.

But then he follows up by saying, "Papa kiss" ... and plants one on Russell. You can also hear the assistant who's holding him say, "Papa Russ?" It's possible the kid was trying to say that and failed. Y'know how 2-year-olds can be.

The social media factor would also add insult to injury ... if you're Future, anyway. Plus, things are already strained -- to say the least -- between Ciara and her baby daddy.

So, we gotta ask ...