fortieth vs ordinal

fortieth and ordinal both are nouns.

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

fortieth (noun)	ordinal (noun)
position 40 in a countable series of things	the number designating place in an ordered sequence

fortieth (adjective)	ordinal (adjective)
the ordinal number of forty in counting order	being or denoting a numerical order in a series
	of or relating to a taxonomic order