percentage vs per centum

percentage and per centum both are nouns.

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

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

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

Other synonyms of percentage include pct, percent.

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