Definition:Epicycloid/Generator/Epicycle

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


 * Epicycloid.png

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

Note on Terminology
The term rotor as used in this context appears to be non-standard.

The term has been taken by from the children's toy Spirograph, which itself was taken from the term rotor as applied to the moving (rotating) part of a a rotary machine.

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 values brevity, it has been decided that this can be remedied.