1590s, "pertaining to the Western Hemisphere and its aboriginal inhabitants," from Modern Latin Americanus, from America (q.v.); the sense of "pertaining to the residents of North America of European (originally British) descent" is first recorded 1640s; later "pertaining to the United States." French Américain, Spanish and Italian Americano, German Amerikanisch. Fem. form Americaness attested from 1838. The American beauty rose so called from 1886. American English as a sub-language attested from 1806; Amerenglish is from 1974.
1640s, "pertaining to or being a center," also "being that from which other related things proceed," from French central or directly from Latin centralis "pertaining to a center," from centrum (see center (n.)). Centrally is attested perhaps as early as early 15c., which might imply a usage of central earlier than the attested date.
Slightly older is centric (1580s). As a U.S. colloquial noun for "central telephone exchange," first recorded 1889 (hence, "Hello, Central?"). Central processing unit attested from 1961. Central America is attested from 1826.
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]
coined 1931 by James Truslow Adams, U.S. writer and popular historian (unrelated to the Massachusetts Adamses), in "Epic of America."
[The American Dream is] that dream of a land in which life should be better and richer and fuller for everyone, with opportunity for each according to ability or achievement. It is a difficult dream for the European upper classes to interpret adequately, and too many of us ourselves have grown weary and mistrustful of it. It is not a dream of motor cars and high wages merely, but a dream of social order in which each man and each woman shall be able to attain to the fullest stature of which they are innately capable, and be recognized by others for what they are, regardless of the fortuitous circumstances of birth or position. [Adams]
Others have used the term as they will.
The term "anti-American" is a loose one, and loosely employed. My own working definition of it, admittedly a slack one also, is that a person is anti-American if he or she is consistently contemptuous of American culture and furthermore supports any opponent of U.S. policy, whoever this may be. [Christopher Hitchens, review of "The Life of Graham Greene, Vol. II," The Atlantic, March 2005]