The Collaborative International Dictionary of English v.0.48:

Elliptic \El*lip"tic\, Elliptical \El*lip"tic*al\, a. [Gr. ?:
   cf. F. elliptique. See Ellipsis.]
   1. Of or pertaining to an ellipse; having the form of an
      ellipse; oblong, with rounded ends.
      [1913 Webster]

            The planets move in elliptic orbits.  --Cheyne.
      [1913 Webster]

            The billiard sharp who any one catches,
            His doom's extremely hard
            He's made to dwell
            In a dungeon cell
            On a spot that's always barred.
            And there he plays extravagant matches
            In fitless finger-stalls
            On a cloth untrue
            With a twisted cue
            And elliptical billiard balls!
                                                  --Gilbert and
                                                  Sullivan (The
                                                  Mikado: The
                                                  More Humane
                                                  Mikado Song)

   2. Having a part omitted; as, an elliptical phrase.
      [1913 Webster]

   3. leaving out information essential to comprehension; so
      concise as to be difficult to understand; obscure or
      ambiguous; -- of speech or writing; as, an elliptical
      comment.
      [PJC]

   Elliptic chuck. See under Chuck.

   Elliptic compasses, an instrument arranged for drawing
      ellipses.

   Elliptic function. (Math.) See Function.

   Elliptic integral. (Math.) See Integral.

   Elliptic polarization. See under Polarization.
      [1913 Webster]

WordNet (r) 3.0 (2006):

elliptic
    adj 1: (of a leaf shape) in the form of an ellipse
    2: rounded like an egg [syn: egg-shaped, elliptic,
       elliptical, oval, oval-shaped, ovate, oviform,
       ovoid, prolate]
    3: characterized by extreme economy of expression or omission of
       superfluous elements; "the dialogue is elliptic and full of
       dark hints"; "the explanation was concise, even elliptical to
       the verge of obscurity"- H.O.Taylor [syn: elliptic,
       elliptical]