‘A’ and ‘an’ are the two versions of the indefinite article. The pause that ‘an’ adds between two vowel sounds helps us to distinguish separate words in speech. For example, it is much more difficult to say ‘a office’ than ‘an office’. Here, then, we will look at when to use ‘an’ instead of ‘a’ before a word.
Words Beginning with Hard-Sounding Vowels
The basic rule for indefinite articles is that you should use ‘an’ when the word which follows begins with a vowel, but use ‘a’ when the word which follows begins with a consonant.
There are, however, many exceptions to this general rule. Whenever a word beginning with a vowel does not sound like it starts with a vowel, you should use ‘a’ rather than ‘an’.
For example, although the word ‘university’ begins with a vowel, it is pronounced ‘yoo-niversity’ rather than ‘ooh-niversity’. This means that ‘a university’ is correct, but ‘an university’ is incorrect. Another good example is ‘European’:
Free movement is protected by a European Union law. – Correct
Free movement is protected by an European law. – Incorrect
Despite the word ‘European’ beginning with a vowel, like ‘university’, it is pronounced with a harder ‘yoo-’ sound, meaning an ‘a’ should be used.
Words Beginning with Consonants
Similarly, if the word following the article begins with a consonant which does not sound like a consonant when spoken, you should use ‘an’ instead of ‘a’.
Take, for example, the word ‘hour’. The ‘h’ in ‘hour’ is typically silent, so we would say ‘an hour’ rather than ‘a hour’.
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Some also recommend using ‘an’ for other words beginning with an ‘h’, such as ‘hotel’ or ‘historical’. This is because these words used to be pronounced with a silent ‘h’ (and still are sometimes).
In America, for example, the word ‘herb’ is often pronounced ‘urb’, so ‘an herb’ would be correct. However, this is becoming less common, so the general rule should always be to use ‘a’ when a word sounds like it begins with a consonant, and ‘an’ when it sounds like it starts with a vowel.
Abbreviations, Acronyms and Initialisms
The rules above also apply to abbreviations, acronyms and initialisms. Essentially, the indefinite article to use depends on how the abbreviation is pronounced. For instance, we could say:
I attended a Nasa press conference.
Here, we use ‘a’ because ‘Nasa’ is pronounced as a single word with a consonant sound at the start. But if an abbreviation starts with a vowel sound, we would use ‘an’ instead of ‘a’:
We are releasing an LP record of the album next month.
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