Which anatomical action term indicates "movement away from midline"?

The term that signifies "movement away from midline" is abduction. In anatomical terminology, abduction refers to the action of moving a limb or other part away from the median plane of the body, which essentially means increasing the angle between the limb and the body. For example, when you lift your arm sideways away from your body, you are abducing it.

Understanding this concept is crucial because it contrasts with adduction, which describes movement toward the midline. Flexion involves decreasing the angle between two body parts, as seen when bending a joint, and rotation refers to the pivoting of a body part around its axis. Thus, abduction is specifically characterized by its action of moving away from the center or midline of the body.