mediastinum vs cavum

mediastinum and cavum both are nouns.

Word	Noun	Adjective	Verb	Adverb
mediastinum	Yes	No	No	No
cavum	Yes	No	No	No

As nouns, cavum is a hypernym of mediastinum; that is, cavum is a word with a broader meaning than mediastinum:

mediastinum: the part of the thoracic cavity between the lungs that contains the heart and aorta and esophagus and trachea and thymus
cavum: (anatomy) a natural hollow or sinus within the body

Other hypernyms of mediastinum include bodily cavity, cavity.

mediastinum (noun)	cavum (noun)
the part of the thoracic cavity between the lungs that contains the heart and aorta and esophagus and trachea and thymus	(anatomy) a natural hollow or sinus within the body