foci: "FOE-sigh"; plural of focus.
An ellipse with high eccentricity is long and narrow, and the two foci are near the ends of the ellipse.	An ellipse with low eccentricity is more nearly circular, and the two foci are nearer the center of the ellipse.	An ellipse with zero eccentricity is a circle, and the two foci merge to a single focus at the center.