An

An [an'(d)]
From Middle English an, from Old English ān (“an”). More at one.
== Article ==
An (indefinite)
#Form of a (all article senses).
##Used before a vowel sound. quotations
##I'll be there in half an hour.
##(rare or dialectal) Used before /h/ in an unstressed syllable. quotations
##(now quite rare) Used before one and words with initial u, eu. quotations
##(nonstandard) Used before /h/ in a stressed syllable.
##(nonstandard, Britain, West Country) Used before all consonants.
== Notes ==
In standard English, the article an is used before vowel sounds, while a is used before consonant sounds. Alternatively, ancan be found before an unstressed syllable beginning with an h-sound, as in an historic. The h may then become silent or is at least very weakly articulated. This usage is favoured by only 6% of British speakers, and is only slightly more common in writing.
Historically, an could also be found before one and many words with initial u, eu (now pronounced with initial /juː/, /jʊ/, /jə/), such as eunuch, unique, or utility; this is still occasionally encountered. This is as these words formerly started with a vowel sound, though the writing of an before words spelt with initial u, eu was usual until the 19th century, long after these words have acquired initial consonant sounds in standard English.
In the other direction, a can rarely be found before a vowel in nonstandard (often dialectal) speech and written representations thereof, as in "ain't this a innerestin sitchation" (Moira Young, Blood Red Road).
The various article senses of a are all senses of an.
Category:Definite Articles
Category:A