Meaning of AN in English

AN

■ determiner the form of the indefinite article (see a 1 ) used before words beginning with a vowel sound.

Usage

It is better to use a rather th~ ~ before words such as hotel ~d historical that begin with a sounded h- . An was common in the 18th ~d 19th centuries because the initial h was then often not pronounced.

Concise Oxford English vocab.      Сжатый оксфордский словарь английского языка.