Definition:Bilateral Symmetry/Plane Figure

Definition

Let $F$ be a plane geometric figure.

Let there exist a reflection $R$ in an axis of reflection $AB$ such that $\map R F$ is a (reflectional) symmetry.

Then $F$ has (plane) bilateral symmetry about $AB$.

Axis of Bilateral Symmetry

Let $F$ be a plane geometric figure.

Let $\map R F$ be a bilateral symmetry in an axis of reflection $AB$.

Then $AB$ is referred to as an axis of bilateral symmetry of $F$.

Also see

• Results about bilateral symmetry can be found here.

Linguistic Note

The word bilateral derives from the Latin bis (meaning ‎twice) and laterālis (meaning pertaining to the side).

It literally translates as two-sided.

Sources

• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): bilateral symmetry