fifteenth vs ordinal

fifteenth and ordinal both are nouns.

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

fifteenth (noun)	ordinal (noun)
position 15 in a countable series of things	the number designating place in an ordered sequence

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