no. vs ordinal

no. and ordinal both are nouns.

Word	Noun	Adjective	Verb	Adverb
no.	Yes	No	No	No
ordinal	Yes	Yes	No	No

As nouns, no. and ordinal are synonyms defined as:

Other synonyms of no. include ordinal number.

no. (noun)	ordinal (noun)
the number designating place in an ordered sequence	the number designating place in an ordered sequence

no. (adjective)	ordinal (adjective)
	being or denoting a numerical order in a series
	of or relating to a taxonomic order