The difference between Meridional and Septentrional

Meridional as an adjective:

Located in the south, southern; later especially, pertaining to the south of France or other southern parts of Europe.

Meridional as an adjective (astronomy, geography):

Along a north-south direction, or relative to a meridian; or relating to meridians or a meridian.

Meridional as an adjective:

Of or characteristic of southern areas or people, especially those in the south of France or other southern parts of Europe.

Meridional as a noun:

An inhabitant of a southern region, especially the south of France.

Septentrional as an adjective (rare, literary):

Pertaining to the north; northern.