meridional vs meridian

meridional is not a noun while meridian is a noun.

Word	Noun	Adjective	Verb	Adverb
meridional	No	Yes	No	No
meridian	Yes	Yes	No	No

meridional (noun)	meridian (noun)
	an imaginary great circle on the surface of the earth passing through the north and south poles at right angles to the equator
	the highest level or degree attainable; the highest stage of development

meridional (adjective)	meridian (adjective)
of or relating to a meridian	of or happening at noon
located in the south or characteristic of southern people or places	being at the best stage of development