Definitions of ellipse terms
- directrix
- Either line with the property that the ratio of distances from any point on the ellipse to the focus nearer the line and to the line is constant.
- directrices
- Plural of directrix. The two lines that have the directrix property.
- eccentricity ("ek-sen-TRI-si-tee")
- The constant ratio of distances from any point on the ellipse to a foucs and the directrix nearer the focus.
