[ad. Gr. ἔλλειψις, n. of action f. ἐλλείπειν to come short. (In the case of the ellipse regarded as a conic section the inclination of the cutting plane to the base ‘comes short of,’ as in the case of the hyperbola it exceeds, the inclination of the side of the cone.)]
Not in Johnson, Todd, or Richardson (1836); for early examples of the pl. ellipses see ELLIPSIS.
1. A plane closed curve (in popular language a regular oval), which may be defined in various ways: a. Considered as a conic section; the figure produced when a cone is cut obliquely by a plane making a smaller angle with the base than the side of the cone makes with the base. b. A curve in which the sum of the distances of any point from the two foci is a constant quantity. c. A curve in which the focal distance of any point bears to its distance from the directrix a constant ratio smaller than unity.
The planetary orbits being (approximately) elliptical, ellipse is sometimes used for ‘orbit’ (of a planet).
1753. Chambers, Cycl. Supp., s.v. Ellipsis, [The form ellipse is used throughout; the Cycl. 1751 has only ellipsis].
1815. Hutton, Math. Dict., Ellipse or Ellipsis.
1842. Tennyson, Gold. Year, 24. The dark Earth follows wheel’d in her ellipse.
1868. Lockyer, Guillemin’s Heavens (ed. 3), 120. A circle seen obliquely or perspectively shows the form of an ellipse.
1880. C. & F. Darwin, Movem. Pl., 1. Other irregular ellipses … are successively described.
2. transf. An object or figure bounded by an ellipse. Also fig.
1857. Bullock, trans. Cazeaux’s Midwifery, 29. The abdominal strait has been … compared to an ellipse.
1869. Dunkin, Midn. Sky, 163. An ellipse of small stars.
3. Gram. = ELLIPSIS 2. Somewhat rare.
1843–83. Liddell & Scott, Gr. Lex., s.v., Ἔλλειψις.
1886. Roby, Lat. Gram., II. (ed. 5), 511 (Index).
