A and an: when to use them

When to use determiners 'a' and 'an'

By Mary Morel

If the first sound of the following word is a vowel sound (whether or not the letter is a vowel), use an.

an elephant, an hour, an honour, an urn

If the first sound of the following word is a consonant sound (whether or not the letter is a consonant), use a.

a helicopter, a hotel, a union

Using this rule, use an with acronyms such as MRI and STD. (MRI stands for magnetic resonance imaging and STD for sexually transmitted disease.)

an HIV patient (human immunodeficiency virus)

A and an are known as determiners. They are also called indefinite articles. The, which is also a determiner, is commonly called the definite article.

Learn more

If you have English as your second language, you may find determiners difficult.

Why not register for my online course, ESL Grammar (A$39)?

It focuses on determiners, prepositions and tenses.

Read the full list of the Online Writing Training courses.

 
 

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