Indefinite article 'a'
The indefinite articles a and an are used before a singular countable noun which is unspecified, that is a noun that does not refer to a specific person, animal or thing and has not been mentioned before. The indefinite articles are not used before a plural noun or an uncountable noun. A is used before a word that begins with a consonant. An is used before a word that begins with a vowel, or a word that begins with a consonant but has vowel sound (e.g. hour, honour, etc)
When a is used before a noun, it does not refer to that one specific noun; it uses this noun as representing all the others.
Example 1: A house in that new housing estate has at least three bedrooms.
(The article a does not point out a specific house but all houses in that housing estate.)
Examples 2: I want to buy a table.
(The use of a here indicates no special preference for a type of table or a specific table in mind to buy.)
We use a:
when we mention something for the first time:
- I saw a fairy.
- Last night, I heard a scream.
to mean one single person or thing:
- A stranger approached me for some money.
- She has a big mole on her left cheek.
and one interchangeably:
- I lost a hundred/one hundred dollars in the game.
- He keeps a dozen/one dozen green snakes as pets.
before a word which begins with a consonant:
- There is a policeman asking for you.
- It’s a video of a mongoose fighting a snake.
before a word with a long sound of u:
- a university, a uniform, a useful book, a European, a unique design.
- It would be a unique opportunity to travel in space.
before the word one because one sounds as if it begins with a W (wun):
- a one-way street, a one-eyed monster, a one-year course, a one-week holiday.
- I have a one-way ticket to travel from one place to another in the city.
The indefinite article a also means one. We can use a or one as follow:
We use a:
to express a degree, number or amount of something:
- We’re getting a bit bored with nothing to do.
- A little training is all that is required to do the work.
to show that someone or something belongs to a class of people or things:
- She is a doctor. (A profession)
- He is a Belarusian. (A native or national)
with a partitive before an uncountable noun:
- There was a layer of fine dust on the bookshelf.
- They usually have a pint of beer at lunchtime.
with illnesses or conditions: a backache, a cold, a cough, a fever, a headache, a sore throat, a stomach ache, a toothache, etc.to express a degree, number or amount of something:
- She caught a cold while camping.
- He developed a headache from staying up late for successive nights.
- A BA (Bachelor of Arts), a PhD (Doctor of Philosophy)
Sometimes, it is better to use a instead of one.
- She wiped up the vomit with a mop.
- Better than: She wiped up the vomit with one mop.
- He had a bath before he went to bed.
- Better than: He had one bath before he went to bed.
We can use a in front of a proper noun when referring to someone, or when the proper noun is used as an adjective.
- A Mr Brown called to ask when you are going to give back the borrowed money.
- There was a Mr Carter who went from house to house soliciting donations for a charity.
- I still remember it was on a December morning when you drove through the fog into a tree.
- We agreed to meet again on a Saturday afternoon.
Indefinite article a is also used before a word that begins with a vowel but with a consonant sound (a eulogy, a European country, a unanimous verdict, a uniform, a union, a unique opportunity, a universal truth, a university student, a used car, a useful tool, a useless attempt).
- This is a U.
- ‘Pass away’ is a euphemism for ‘die’.
- She no longer sports a unisex haircut.
- I couldn’t make a U-turn as I was driving on a motorway.
- A one-minute silence was observed at the site where the victims were found.
Indefinite article 'an'
The indefinite article an is used before a vowel sound (an apple, an empty can, an inside job), and an unspecified count noun, that is a noun that has not been mentioned before. Do not use an before a plural noun or an uncountable noun, but only before a singular countable noun. The article an does not refer to a specific person or thing.
We use an:
before a noun which begins with a vowel:
- They say an apple a day keeps the doctor away.
- He has an oval-shaped burn scar on his arm.
- That must be an oak tree, which is bigger than all the other trees around here.
before a singular noun (person or thing) to mean only one in quantity.
- There is an egg in the nest.
- She’s an only child.
- An ostrich has only two toes on each foot.
before a noun that is representative of a group, species, etc.
- It is an opal. (A precious stone)
- He is an optician. (A profession)
- She’s an Armenian. (A native or national)
before a word that begins with a consonant but with a vowel sound, especially the h consonant. Examples include an heir, an honest person, an honour, an honourable fellow, an hourly bus service.
- In an hour’s time, the party will be in full swing.
- Each of them received an honour for their services in the rescue mission.
- I can't read your writing. Is this an h or what?
before abbreviations, some of which begin with a consonant.
- I had an X-ray on my lungs.
- I saw an UFO hovering above my kitchen.
- The response was quick to an SOS sent by a ship.
- You must fix an L-plate not only to the back but also to the front of your car.
- His father has an MSc (Master of Science) in Chemistry, and his mother has an MA (Master of Arts) in English literature.
- He always wanted to be an MP but was not elected for the past twelve years.
Words beginning with u and h:
Using a and an with words beginning with u.
A and an are used before words beginning with u: a is used if the u is a consonant sound; an is used if the u has a vowel sound.
- He applied to a university to study palmistry.
- Mom has a unique talent for ghost storytelling.
- He had an uncle who was a great disco dancer.
- She wore a raincoat and carried an umbrella.
- You really believe an ugly witch has magic powers?
- The scientists discovered an unusual insect that flew without wings.
Using a and an with words beginning with h
A and an are used before words beginning with h: a is used if the h is pronounced; an is used if the h is not pronounced.
- We met at a hotel.
- We argued the whole night over where to have a holiday this year.
- After an hour, she recovered enough to speak on stage..
- He claimed he's an honest politician.