The Collaborative International Dictionary of English v.0.48:

ecliptic \e*clip"tic\ ([-e]*kl[i^]p"t[i^]k), n. [Cf. F.
   ['e]cliptique, L. linea ecliptica, Gr. 'ekleiptiko`s, prop.
   adj., of an eclipse, because in this circle eclipses of the
   sun and moon take place. See Ecliptic, a.]
   1. (Astron.) A great circle of the celestial sphere, making
      an angle with the equinoctial of about 23[deg] 28'. It is
      the apparent path of the sun, or the real path of the
      earth as seen from the sun.
      [1913 Webster]

   2. (Geog.) A great circle drawn on a terrestrial globe,
      making an angle of 23[deg] 28' with the equator; -- used
      for illustrating and solving astronomical problems.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ecliptic \E*clip"tic\, a. [L. eclipticus belonging to an
   eclipse, Gr. 'ekleiptiko`s. See Eclipse.]
   1. Pertaining to the ecliptic; as, the ecliptic way.
      [1913 Webster]

   2. Pertaining to an eclipse or to eclipses.
      [1913 Webster]

   Lunar ecliptic limit (Astron.), the space of 12[deg] on the
      moon's orbit from the node, within which, if the moon
      happens to be at full, it will be eclipsed.

   Solar ecliptic limit, the space of 17[deg] from the lunar
      node, within which, if a conjunction of the sun and moon
      occur, the sun will be eclipsed.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ecliptic
    n 1: the great circle representing the apparent annual path of
         the sun; the plane of the Earth's orbit around the sun;
         makes an angle of about 23 degrees with the equator; "all
         of the planets rotate the sun in approximately the same
         ecliptic"