per centum vs percentage

per centum and percentage both are nouns.

Word	Noun	Adjective	Verb	Adverb
per centum	Yes	No	No	No
percentage	Yes	No	No	No

As nouns, per centum and percentage are synonyms defined as:

per centum and percentage: a proportion in relation to a whole (which is usually the amount per hundred); ten percent

Other synonyms of per centum include pct, percent.

per centum (noun)	percentage (noun)
a proportion in relation to a whole (which is usually the amount per hundred); ten percent	assets belonging to or due to or contributed by an individual person or group
	a proportion in relation to a whole (which is usually the amount per hundred); ten percent