The Collaborative International Dictionary of English v.0.48:

Abdominal \Ab*dom"i*nal\, a. [Cf. F. abdominal.]
   1. Of or pertaining to the abdomen; ventral; as, the
      abdominal regions, muscles, cavity.
      [1913 Webster]

   2. (Zool.) Having abdominal fins; belonging to the
      Abdominales; as, abdominal fishes.
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   Abdominal ring (Anat.), a fancied ringlike opening on each
      side of the abdomen, external and superior to the pubes;
      -- called also inguinal ring.
      [1913 Webster]