abdominal vs oblique

abdominal and oblique both are nouns.

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

As nouns, oblique is a hyponym of abdominal; that is, oblique is a word with a more specific, narrower meaning than abdominal:

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

abdominal (adjective)	oblique (adjective)
of or relating to or near the abdomen	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