superior vena cava vs precava

superior vena cava and precava both are nouns.

Word	Noun	Adjective	Verb	Adverb
superior vena cava	Yes	No	No	No
precava	Yes	No	No	No

As nouns, superior vena cava and precava are synonyms defined as:

superior vena cava and precava: receives blood from the head and arms and chest and empties into the right atrium of the heart; formed from the azygos and both brachiocephalic veins

superior vena cava (noun)	precava (noun)
receives blood from the head and arms and chest and empties into the right atrium of the heart; formed from the azygos and both brachiocephalic veins	receives blood from the head and arms and chest and empties into the right atrium of the heart; formed from the azygos and both brachiocephalic veins