ELLIPSE, or ELLIPSIS

ELLIPSE, or ELLIPSIS, is one of the conic sections,

tions, popularly called an oval; being called an ellipse or ellipsis by Apollonius, the first and principal author on the conic sections, because in this figure the squares of the ordinates are less than, or defective of, the rectangles under the parameters and abscissæ. See Conic Sections, Encycl.