What is the anatomical term for movement that decreases the angle between body parts?

The anatomical term for movement that decreases the angle between body parts is flexion. This movement typically brings two body parts closer together, resulting in a smaller angle at the joint. For example, when you bend your elbow to bring your hand towards your shoulder, you are performing flexion.

In contrast, adduction refers to the movement toward the midline of the body, extension increases the angle between body parts (like straightening the arm), and abduction involves moving a body part away from the midline. Therefore, flexion is distinctly defined as the action that reduces the angle, making it the correct choice in this context.