# Definition:Epicycloid/Generator

## Definition

Let an epicycloid be generated by rolling a circle $C_1$ around the outside of another circle $C_2$.

The circles $C_1$ and $C_2$ can be referred to as the **generators** of the epicycloid.

### Stator

The circle $C_2$ can be referred to as the **stator** of the epicycloid.

### Rotor

The circle $C_1$ can be referred to as the **rotor** of the epicycloid.

## Also known as

The **generators** of an epicycloid can also be referred to as its **generating circles**.

## Note on Terminology

The term **generator** as used in this context was coined by $\mathsf{Pr} \infty \mathsf{fWiki}$ to describe this object.

While the literature on epicycloids is extensive, there appears from some cursory web searching that there does not appear to be a standard name for either of the circles involved in their generation.

As the philosophy of $\mathsf{Pr} \infty \mathsf{fWiki}$ values brevity, it has been decided that this can be remedied.