epicycloid
Concise Oxford English Dictionary © 2008 Oxford University Press:
epicycloid /ˌɛpɪˈsʌɪklɔɪd/
▶noun Mathematics a curve traced by a point on the circumference of a circle rolling on the exterior of another circle.
– derivatives
epicycloidal adjective.
epicycloidal adjective.
'epicycloid' also found in these Oxford entries:

