— epicycloidal , adj.
/ep'euh suy"kloyd/ , n. Geom.
a curve generated by the motion of a point on the circumference of a circle that rolls externally, without slipping, on a fixed circle. Equation: x = ( a + b ) cos(t) - b cos [( a + b )t/ b ] and y = ( a + b ) sin(t) - b sin [( a + b )t/b]. Cf. epitrochoid .
[ 1780-90; EPICYCLE + -OID ]