"A" or "An"?

Use 'an' before a word that starts with a vowel sound. If it does not start with a vowel sound, use 'a'. For example:

• A man

• An elephant

But, look at this:

• A house

• An hour

The key word here is sound. It is not a question of whether the word starts with a vowel. It is a question of whether it starts with a vowel sound.

Using A and An

There is sometimes confusion about whether to use an or a, particularly with abbreviations. (The words an and a are known as articles.) The sound of a word's first letter determines which to use. If the word starts with a vowel sound, you should use an. If it starts with a consonant sound, you should use a. Examples:

• Buy a house in an hour.

• (Although house and hour start with the same three letters (hou), one attracts a and the other an.)

• An unknown goblin killed a unicorn.

• (Although unknown and unicorn start with the same two letters (un), one attracts 'an' and the other 'a'. Remember, it is about the sound of the first letter.)

• An LRS... (LRS = Linear Recursive Sequence)

• A TT race... (TT = Tourist Trophy)

• It would be an honour. (The word honour starts with an o sound.)

• Send a US ambassador. (The abbreviation US starts with a y sound.)

• She was involved in a RTA. (RTA = Road Traffic Accident) (The abbreviation 'RTA' starts with an 'a' sound (i.e., ar-tee-ay.)