What anatomical term describes a movement toward the midline of the body?

The anatomical term that describes a movement toward the midline of the body is adduction. This term is used to indicate the action of bringing a limb or body part closer to the center line of the body. For instance, when you lower your arms towards your sides from an outstretched position, you are performing adduction.

In the context of movement, adduction contrasts with abduction, which refers to moving a limb away from the midline. Flexion and extension are terms that describe bending and straightening motions, respectively, typically at a joint, and are not related to the position of a body part in relation to the midline. Therefore, adduction is the correct term for the movement in question.