A an: Encyclopedia II - A an - An

A an - An

An is the older form, now used before words starting with a vowel sound, regardless of whether the word begins with a vowel letter. Examples: a light-water reactor; an LWR; a HEPA filter (because HEPA is pronounced as a word rather than as letters); a hypothesis; an hour.[1] However, it is still often considered proper to use an before any noun starting with h.

More examples: "a boy, a European, a j, a picture, a store, a table, a bottle, a window, a phone, a hyphen, a one-horse town" and "a united country, a usurper, a eulogy, a ewe, a U-boat" and "an entry, an f, an hour, an orange, an ape, an odor, an idea, an eagle, an honor, an umbrella, an unbeliever" and "a hotel, a house, a hill, a hymn, a honeycomb". [2]

"Merriam-Webster's Dictionary of English Usage is more descriptive than prescriptive, but it advises: You choose the article that suits your own pronunciation. Theodore Bernstein gives the straight vowel-sound-vs.-consonant-sound explanation but allows that you should indeed say "an hotel" if you think hotel is pronounced otel." [3]

Adapted from the Wikipedia article "An", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki