What does abdominal mean?
The definition of abdominal
Ab*dom”i*nal, a.
Etym: [Cf. F. abdominal.]

1 Of or pertaining to the abdomen; ventral; as, the abdominal regions, muscles, cavity.
2 (Zoöl.)
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.

Ab*dom”i*nal, n.; E. pl. Abdominals, L. pl. Abdominales.
A fish of the group Abdominales.