# Definition:Bilateral Symmetry

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## Definition

Let $F$ be a geometric figure.

Let there exists a reflection $R$ in the such that $\map R F$ is a symmetry.

Then $F$ has **bilateral symmetry**.

### Axis of Symmetry

Let $F$ be a plane geometric figure.

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

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

## 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

- 1986: David Wells:
*Curious and Interesting Numbers*... (previous) ... (next): $2$ - 1997: David Wells:
*Curious and Interesting Numbers*(2nd ed.) ... (previous) ... (next): $2$