ostiary vs ostiarius

ostiary and ostiarius both are nouns.

Word	Noun	Adjective	Verb	Adverb
ostiary	Yes	No	No	No
ostiarius	Yes	No	No	No

As nouns, ostiary and ostiarius are synonyms defined as:

ostiary and ostiarius: the lowest of the minor Holy Orders in the unreformed Western Church but now suppressed by the Roman Catholic Church

Other synonyms of ostiary include doorkeeper.

ostiary (noun)	ostiarius (noun)
someone who guards an entrance	the lowest of the minor Holy Orders in the unreformed Western Church but now suppressed by the Roman Catholic Church
the lowest of the minor Holy Orders in the unreformed Western Church but now suppressed by the Roman Catholic Church