ordinal vs tertiary

ordinal is a noun but tertiary is not a noun.

Word	Noun	Adjective	Verb	Adverb
ordinal	Yes	Yes	No	No
tertiary	No	Yes	No	No

ordinal (noun)	tertiary (noun)
the number designating place in an ordered sequence

ordinal (adjective)	tertiary (adjective)
being or denoting a numerical order in a series	coming next after the second and just before the fourth in position
of or relating to a taxonomic order