Flexion is bending, most often ventrally to decrease the angle between two parts of the body; it is usually an action at an articulation or joint.
Extension is straightening, or increasing the angle between two parts of the body; a stretching out or making the flexed part straight.
Abduction is a movement away from the midsagittal plane (midline); to adduct is to move medially and bring a part back to the mid-axis.
Circumduction is a circular movement at a ball and socket (shoulder or hip) joint, utilizing the movements of flexion, extension, abduction, and adduction.
Rotation is a movement of a part of the body around its long axis.
Supination refers only to the movement of the radius around the ulna. In supination the palm of the hand is oriented anteriorly; turning the palm dorsally puts it into pronation. The body on its back is in the supine position.
Pronation refers to the palm of the hand being oriented posteriorly. The body on its belly is the prone position.
Inversion refers only to the lower extremity, specifically the ankle joint. When the foot (plantar surface) is turned inward, so that the sole is pointing and directed toward the midline of the body and is parallel with the median plane, we speak of inversion. Its opposite is eversion.
Eversion refers to the foot (plantar surface) being turned outward so that the sole is pointing laterally.
Opposition is one of the most critical movements in humans; it allows us to have pulp-to-pulp opposition, which gives us the great dexterity of our hands. In this movement the thumb pad is brought to a finger pad. A median nerve injury negates this action.