vena hemizygos vs vena

vena hemizygos and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
vena hemizygos	Yes	No	No	No
vena	Yes	No	No	No

As nouns, vena is a hypernym of vena hemizygos; that is, vena is a word with a broader meaning than vena hemizygos:

vena hemizygos: a continuation of the left ascending lumbar vein; crosses the midline at the 8th vertebra and empties into the azygos vein
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of vena hemizygos include vein, venous blood vessel.

vena hemizygos (noun)	vena (noun)
a continuation of the left ascending lumbar vein; crosses the midline at the 8th vertebra and empties into the azygos vein	a blood vessel that carries blood from the capillaries toward the heart