The term 'UPPER SURFACE OF FOOT' can be summarized by the 6-letter word 'INSTEP'. The instep is the upper surface of the foot, located between the toes and the ankle. It is the curved area of the foot that is visible when looking at the top of the foot. The instep is an important part of the foot's anatomy, as it helps to support the body's weight and provides stability when walking or running.