Source : Webster's Revised Unabridged Dictionary (1913)

Abdominal \Ab*dom"i*nal\, a. [Cf. F. abdominal.]
   1. Of or pertaining to the abdomen; ventral; as, the
      abdominal regions, muscles, cavity.

   2. (Zo["o]l.) Having abdominal fins; belonging to the
      Abdominales; as, abdominal fishes.

   {Abdominal ring} (Anat.), a fancied ringlike opening on each
      side of the abdomen, external and superior to the pubes;
      -- called also {inguinal ring}.

Abdominal \Ab*dom"i*nal\, n.; E. pl. {Abdominals}, L. pl.
   {Abdominales}.
   A fish of the group Abdominales.

Source : WordNet®

abdominal
     n : the muscles of the abdomen [syn: {abdominal muscle}, {ab}]

abdominal
     adj : of or relating to or near the abdomen; "abdominal muscles"