millionth vs ordinal

millionth and ordinal both are nouns.

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

millionth (noun)	ordinal (noun)
one part in a million equal parts	the number designating place in an ordered sequence
position 1,000,000 in a countable series of things

millionth (adjective)	ordinal (adjective)
the ordinal number of one million in counting order	being or denoting a numerical order in a series
	of or relating to a taxonomic order