Americanism

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A custom, trait, or tradition originating in the United States.
• noun A word, phrase, or idiom characteristic of English as it is spoken in the United States.
• noun Allegiance to the United States and its customs and institutions.

from The Century Dictionary.

• noun Devotion to or preference for the United States and their institutions; preference for whatever is American in this sense; the exhibition of such preference.
• noun The condition of being a citizen of the United States.
• noun A custom, trait, or thing peculiar to America or Americans; in general, any distinctive characteristic of American life, thought, literature, etc.
• noun A word, a phrase, or an idiom of the English language which is now peculiar to or has originated in the United States.
• noun A name applied to a series of opinions at variance with the policy and practice of the Roman Catholic Church, supposed for a time to be held by some members of that church, especially in the United States, and condemned by Pope Leo XIII. in 1899 in an apostolical letter addressed to Cardinal Gibbons.

from the GNU version of the Collaborative International Dictionary of English.

• noun Attachment to the United States.
• noun A custom peculiar to the United States or to America; an American characteristic or idea.
• noun A word or phrase peculiar to the United States.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A custom peculiar to the United States or the Americans.
• noun A word, phrase or linguistic feature originating from or specific to American language usage.
• noun A preference to the United States and the ideas it represents.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a custom that is peculiar to the United States or its citizens
• noun an expression that is characteristic of English as spoken by Americans
• noun loyalty to the United States and its institutions