ellipse

ellipsi puhekieltä A closed curve, the locus of a point such that the sum of the distances from that point to two other fixed points (called the focus foci of the ellipse) is constant; equivalently, the conic section that is the intersection of a cone with a plane that does not intersect the base of the cone.
puhekieltä To remove from a phrase a word which is grammatically needed, but which is clearly understood without having to be stated.

In Bs response to A's question:- (A: Would you like to go out?, B: I'd love to), the words that are ellipsed are go out.''