Board Thread:Mortal Kombat X/@comment-25163804-20141113230845/@comment-21005855-20141119213208

"A cyborg (short for "cybernetic organism") is a being with both organic and biomechatronic parts."

That is a direct quote from Wikipedia.org. You can look it up in other media forms but you'll find the same thing.

Jax being a guy with mecanical arms is considered a cyborg just like Cyrax, Sektor, Smoke (original timeline), Sub-Zero (alternate timeline), Kano, Hsu Hao, etc.