- an ► DETERMINER ▪ the form of ‘a’ (the indefinite article) used before words beginning with a vowel sound.USAGE There is some divergence of opinion over whether to use a or an before certain words beginning with h- when the first syllable is unstressed (eg. historical and hotel). The form depends on whether the initial h is sounded or not: an was formerly common because h was not usually pronounced for these words. In current English the norm is for the initial h to be pronounced, and therefore the indefinite article a is used; however, the older form, with the silent h and an, is still encountered.
English terms dictionary. 2015.