To turn a description into something perceivable. Rendering adds no meaning and decides how meaning arrives.
Old French rendre, from Latin reddere (to give back): red- (back) + dare (to give); to render is to give a description back as something that can actually be perceived, adding nothing to what was described.
To turn a description into something perceivable. The root's giving-back is exact: rendering adds no meaning of its own, it only decides the form the existing meaning arrives in.