abdomen vs bodily cavity

abdomen and bodily cavity both are nouns.

Word	Noun	Adjective	Verb	Adverb
abdomen	Yes	No	No	No
bodily cavity	Yes	No	No	No

As nouns, bodily cavity is a hypernym of abdomen; that is, bodily cavity is a word with a broader meaning than abdomen:

abdomen: the cavity containing the major viscera; in mammals it is separated from the thorax by the diaphragm
bodily cavity: (anatomy) a natural hollow or sinus within the body

Other hypernyms of abdomen include cavity, cavum.

abdomen (noun)	bodily cavity (noun)
the region of the body of a vertebrate between the thorax and the pelvis	(anatomy) a natural hollow or sinus within the body
the cavity containing the major viscera; in mammals it is separated from the thorax by the diaphragm