The Collaborative International Dictionary of English v.0.48:

Ellipsis \El*lip"sis\ ([e^]l*l[i^]p"s[i^]s), n.; pl. Ellipses
   ([e^]l*l[i^]p"s[=e]z). [L., fr. Gr. 'e`lleipsis a leaving,
   defect, fr. 'ellei`pein to leave in, fall short; 'en in +
   lei`pein to leave. See In, and Loan, and cf. Ellipse.]
   1. (Gram.) Omission; a figure of syntax, by which one or more
      words, which are obviously understood, are omitted; as,
      the virtues I admire, for, the virtues which I admire.
      [1913 Webster]

   2. (Geom.) An ellipse. [Obs.]
      [1913 Webster]

   3. (Printing) a printing symbol, usually three periods in a
      row (. . .), indicating the omission of some part of a
      text; -- used commonly in quotations, so as to suppress
      words not essential to the meaning. A long dash (---) and
      three asterisks (* * *) are sometimes used with the same
      meaning.
      [PJC]