Cris "Cyborg" Justino ain't mincing her words ... telling TMZ Sports she would "kill" Ronda Rousey if they ever stepped in the Octagon.
The UFC superstar was at LAX when she made it clear -- she has a burning desire to fight Ronda because they have a "novella" together ... "and you have to finish a novella."
So, how would the novella end?
"I kill her," Cyborg says ... "I would put everything [she has said] about me in my hands."
We also asked about Miesha Tate -- who recently told TMZ Sports she'd definitely take a fight with Cyborg.
Cyborg's reaction -- bring it on!