Boston Bombing Survivor -- Boxing Training ... With George Foreman's Son!

Another bad ass notch on Adrianne Haslet's belt ... 'cause the woman who lost her leg in the Boston Marathon bombing -- is now BOXING with George Foreman's son!

Haslet was training with George Foreman III earlier this week at his EverybodyFights boxing gym in Boston.

FYI, GF3 was a pretty good boxer himself -- racking up a 16-0 record as a pro.

It's another impressive feat for Haslet -- who already completed the 2016 Boston Marathon on a prosthetic leg ... and picked up ballroom dancing again after the incident.

#BostonStrong