Using An and A (especially with Abbreviations and Acronyms)
The Quick AnswerUse 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
- A house
- An hour
Using A and AnThere 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.
- 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 a honour. (The word honour starts with an o sound.)
- Send an 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.)
Beware of AbbreviationsAbbreviations that start with the consonants F, H, L, M, N, R, S, and X attract an because they start with vowel sounds. For example:
- An FRS representative will be present after lunch. (FRS = Fellow of the Royal Society)
- A LF transmitter was found in the basement. (LF = Low Frequency)
Beware the Letter UAbbreviations that start with the vowel U attract a because U starts with the consonant sound y. For example:
- A US ship spotted a U-boat.
- An UFO landed in 1967.
Treat Acronyms Like Words Not AbbreviationsAn acronym is an abbreviation that is spoken like a word, e.g., BUPA, FOD, FEDEX. Therefore, as the first sound of FEDEX is f, use a and not an.
- Tim worked in the air industry as a FOD inspector for a year. (FOD = Foreign Object Damage)
- Jack was a FEDEX courier.
An Historical or A Historical?Letters and sounds do not always correlate in English.
When pronouncing the words historic and historical, the accent falls on the second syllable, and many pronounce them as starting with a vowel. For those people, it is appropriate to use an before historic and historical. Therefore, you have a choice depending on what sounds best for you.
There is a lot of leniency on this issue. If you're still unsure, opt for a historical and a historic as these remain preferable – especially in formal writing.
Read about the difference between historic and historical.