oblique vs abdominal

oblique and abdominal both are nouns.

Word	Noun	Adjective	Verb	Adverb
oblique	Yes	Yes	No	No
abdominal	Yes	Yes	No	No

As nouns, abdominal is a hypernym of oblique; that is, abdominal is a word with a broader meaning than oblique:

Other hypernyms of oblique include ab, abdominal muscle.

oblique (noun)	abdominal (noun)
a diagonally arranged abdominal muscle on either side of the torso	the muscles of the abdomen
any grammatical case other than the nominative

oblique (adjective)	abdominal (adjective)
slanting or inclined in direction or course or position--neither parallel nor perpendicular nor right-angled	of or relating to or near the abdomen
indirect in departing from the accepted or proper way; misleading