What is the medical term for ex? Ex = out of, from (Latin)Extension= opposite of flexion.
Why is treatment abbreviation TX? 1 Answer. It seems plausible that the medical convention of using 'x' as the second letter of an abbreviation (in, for example, Dx (diagnosis), Sx (symptom or surgery), Fx (family), Hx (history), and Tx (transplant or treatment)) comes from copying ...