Source : Webster's Revised Unabridged Dictionary (1913)

Dorsal \Dor"sal\, a. [F. dorsal, LL. dorsalis, fr. L. dorsualis,
   fr. dorsum back; cf. Gr. ?, ?, mountain ridge. Cf. {Dorse},
   {Dorsel}, {Dosel}.]
   1. (Anat.) Pertaining to, or situated near, the back, or
      dorsum, of an animal or of one of its parts; notal;
      tergal; neural; as, the dorsal fin of a fish; the dorsal
      artery of the tongue; -- opposed to {ventral}.

   2. (Bot.)
      (a) Pertaining to the surface naturally inferior, as of a
          leaf.
      (b) Pertaining to the surface naturally superior, as of a
          creeping hepatic moss.

   {Dorsal vessel} (Zo["o]l.), a central pulsating blood vessel
      along the back of insects, acting as a heart.

Dorsal \Dor"sal\, n. [LL. dorsale, neut. fr. dorsalis. See
   {Dorsal}, a.] (Fine Arts)
   A hanging, usually of rich stuff, at the back of a throne, or
   of an altar, or in any similar position.

Source : WordNet®

dorsal
     adj 1: belonging to or on or near the back or upper surface of an
            animal or organ or part; "the dorsal fin is the
            vertical fin on the back of a fish and certain marine
            mammals" [ant: {ventral}]
     2: facing away from the axis of an organ or organism; "the
        abaxial surface of a leaf is the underside or side facing
        away from the stem" [syn: {abaxial}] [ant: {adaxial}]