pct vs per centum

pct and per centum both are nouns.

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

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

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

Other synonyms of pct include percent, percentage.

pct (noun)	per centum (noun)
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