national adj.

c. 1300, nacioun, "a race of people, large group of people with common ancestry and language," from Old French nacion "birth, rank; descendants, relatives; country, homeland" (12c.) and directly from Latin nationem (nominative natio) "birth, origin; breed, stock, kind, species; race of people, tribe," literally "that which has been born," from natus, past participle of nasci "be born" (Old Latin gnasci), from PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups.

The word is used in English in a broad sense, "a race of people an aggregation of persons of the same ethnic family and speaking the same language," and also in the narrower sense, "a political society composed of a government and subjects or citizens and constituting a political unit; an organized community inhabiting a defined territory within which its sovereignty is exercised."

In Middle English it is not easy to distinguish them, but the "political society" sense emerged by 16c., perhaps late 14c. and it has gradually predominated. The older sense is preserved in the application of nation to the native North American peoples (1640s). Nation-building "creation of a new nation" is attested by 1907 (implied in nation-builder). Nation-state "sovereign country the inhabitants of which are united by language, culture, and common descent" is from 1918.

A nation is an organized community within a certain territory; or in other words, there must be a place where its sole sovereignty is exercised. [Theodore D. Woolsey, "Introduction to the Study of International Law," 1864] 

suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).