oblique vs abdominal muscle

oblique and abdominal muscle both are nouns.

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

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

Other hypernyms of oblique include ab, abdominal.

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