meridian vs date line

meridian and date line both are nouns.

Word	Noun	Adjective	Verb	Adverb
meridian	Yes	Yes	No	No
date line	Yes	No	No	No

meridian (noun)	date line (noun)
an imaginary great circle on the surface of the earth passing through the north and south poles at right angles to the equator	an imaginary line on the surface of the earth following (approximately) the 180th meridian
the highest level or degree attainable; the highest stage of development

meridian (adjective)	date line (adjective)
of or happening at noon
being at the best stage of development