tertiary vs ordinal

tertiary is not a noun while ordinal is a noun.

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

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

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