Boston Marathon Survivor -- DANCING AGAIN ... After Losing Leg In Bombing

This is an AMAZING story ... Adrianne Haslet-Davis -- who lost her left leg in the Boston Marathon bombing -- is DANCING AGAIN after being equipped with a bionic limb.

Adrianne -- a professional ballroom dancer -- appeared at the TED Conference in British Columbia on Wednesday as a guest of Hugh Herr ... the director of the Biomechatronics Group at The MIT Media Lab.

FYI -- Herr spearheaded the project to build a special prosthetic for Adrianne after meeting her at a rehab clinic. The project took 200 days.

At the TED Conference, Herr introduced Adrianne to the crowd and said, "In 3.5 seconds, the criminals and cowards took Adrianne off the dance floor. In 200 days, we put her back."

Adrianne then busted out a rumba with dance partner Chrstian Lightner to Enrique Iglesias' hit "Ring My Bells."

Afterward, Adrianne said, "I'm thrilled to have danced again. I was always determined to dance again, and I knew that I had to, that I would, and here I am."