arc boundary
arc contour
arc silhouette
arc structure
ball boundary
ball profile
ball structure
bubble disk
bubble form
bubble outline
circular design
curve circle
curve form
curved circle
cycle contour
disc circumference
disc structure
disk circumference
ellipse boundary
ellipse form
globe circumference
globe profile
globe silhouette
halo circumference
halo form
hoop boundary
hoop silhouette
loop boundary
loop circumference
loop profile
loop shape
orb frame
orb silhouette
orbit frame
orbit silhouette
oval contour
oval frame
oval silhouette
ring pattern
ring profile
ring silhouette
round form
round frame
sphere circumference
sphere outline
sphere profile
wheel circumference
wheel outline
wheel symmetry