Or symmetry plane, used to describe a repetition of features whereby identical points occur an equal but opposite distance along any line perpendicular from this imaginary plane. Consequently, an object is “bilateral” in that it shows a matching of features (also referred to as “reflection”) but a change in “handedness”, e.g., most people, standing with arms by their sides and feet side-by-side, have a mirror (bilateral or reflection) relationship between the left side and the right side.
Cf., symmetry, center of symmetry, rotation symmetry