An

indefinite article used before a word which starts with a vowel

An is the indefinite article in English; see a and an.
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.an is the Internet country code top-level domain (ccTLD) for Netherlands Antilles. It is administered by the University of the Netherlands Antilles. As the Netherlands Antilles are due to be abolished on December 15, 2008, the future of the .an top-level domain is uncertain.
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Noun
1. an associate degree in nursing
(synonym) Associate in Nursing
(hypernym) associate degree, associate

adj. on, activated, turned on

prep. at, in, on, near; beside, by; inside; atop

n. year; twelvemonth