Which term best describes movement of a limb away from the body's midline?

The term that describes the movement of a limb away from the body's midline is abduction. This term specifically refers to the lateral movement of a body part, such as an arm or leg, away from the central axis of the body. For example, raising your arms to the side stretches them away from your torso, demonstrating abduction.

In contrast, adduction refers to the movement of a limb toward the body’s midline, which is the opposite of abduction. Circumduction is a circular movement that combines flexion, extension, adduction, and abduction, making it distinct from simply moving a limb away from the midline. Flexion, on the other hand, is a movement that decreases the angle between body parts, such as bending an elbow or knee, and does not pertain to the position relative to the midline. Thus, abduction is the correct term for this specific movement.