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.)
 

 

Examples:

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 universitya uniforma useful book, a Europeana 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 also means one. We can use a or one as follow:

Examples:

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.

before abbreviations: 

  • A BA (Bachelor of Arts), a PhD (Doctor of Philosophy)

     

 

 

Sometimes, it is better to use a instead of one.

Examples:

  • 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. 

Examples:

  • 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).

 

Examples:

  • This is 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.
 
 

Examples:

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 and an with words beginning with u.

A and an are used before words beginning with ua is used if the is a consonant sound; an is used if the u has a vowel sound.  

Examples:

  • He applied to a university to study palmistry.
  • Mom has 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 and an with words beginning with h

A and an are used before words beginning with ha is used if the h is pronounced; an is used if the h is not pronounced.
 

Examples:

  • 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.