Indefinite article

An indefinite article is a grammatical article used to express indefiniteness (i.e. lack of definiteness). English has distinct articles for singular indefinite article and plural indefinite article, though the latter is null.

Contrast the definite article.

Meaning

A and an mean “one” or specifically “one of many,” without specifying exactly which one. So, if we say a car we mean “one car of the many cars that exist”. After introducing the object, however, the interlocutors now know which one they’re talking about, so then typically use the definite article the. For example, A car was parked by the side of the road. The car had its lights off.

Form

• A is used before consonant sounds (regardless of spelling)
• An is used before vowel sounds (regardless of spelling).
• The null indefinite article is used for plurals.

That gives the following table:

	Plain case	Genitive case
Common gender singular	a driver	a driver’s
Dual gender singular	a lawyer	a lawyer’s
Feminine singular	a woman an aunt	a woman’s an aunt’s
Masculine singular	a man an uncle	a man’s an uncle’s
Neuter singular	a table an apple	a table’s an apple’s
Common gender plural	Ø drivers	Ø drivers’
Dual gender plural	Ø lawyers	Ø lawyers’
Feminine plural	Ø women	Ø women’s
Masculine plural	Ø men	Ø men’s
Neuter singular	Ø tables	Ø tables’

Usage

An indefinite article can only used with countable singular nouns. It is not particularly “strong,” meaning that other determiners may displace a/an. So, this is superseded by:

• The definite article, the, e.g. a car which we’re discussing = the car.
• Singular possessive determiners, e.g. a car that belongs to me = my car.
• Singular demonstrative determiners, e.g. a car located nearby = this car.
• Singular interrogative determiners, e.g. which car?, what car? or whose car?
• Possessive case nouns, e.g. a car that belongs to Bob = Bob’s car.

A or an?

A is generally used before consonant sounds while an is used before vowel sounds. Note that this reflects speech sounds rather than spelling. So, for example, we:

• Use an before silent H, e.g. an hour not *a hour.
  • Americans will say an herb (with a silent H), but British speakers will say a herb (without a silent H).
• Use a before a long U sound pronounced /ju:/:
  • Spelt beginning with U e.g. a university not *an university.
  • Spelt beginning with eu-, e.g. a euphemism, not *an euphemism.
• Use a before a word beginning /w/ but spelt with an O, e.g. a one-time teacher not *An one-time teacher.

H-dropping is fairly common in colloquial speech, and speakers tend to use an before a dropped H, as they would before a silent H. For example ^!an ‘orse /ən ɔ:s/ (meaning “a horse”).

A few words used to have silent H, but no longer do in contemporary English. These include hotel, horrific and historic; more traditional texts may use an here, but most modern writers will use a.

Pronunciation

The choice of whether to use a or an is determined primarily by pronunciation.

Both a and an have strong forms and weak forms. Generally, the weak form is more common, because articles tend to be unstressed. A has a strong form /eɪ/ but a much more common weak form /ə/ (schwa). Meanwhile, an has a strong form /æn/ and a weak form /ən/.

Spelling

Spelling usually follows pronunciation (see above).

In some cases, especially when we have the possibility of either a or an being used, an indefinite article is represented by a/an or a(n). These are often found in gapfill questions.

Non-English indefinite articles

Indefinite articles from other languages are sometimes used as part of fixed phrases or artistic titles.

• French: un (m) /une (f).
• German: ein (m), eine (f), ein (n).

Pedagogy

The singular indefinite articles are introduced at beginner level. The meaning can be explained simply; “a means one,” or more specifically “a means one of many.”

The plural indefinite articles are null, so are not typically explained to learners.

Low level learners will often say a when they need to say an — this is usually worth correcting. Intermediate and advanced speakers sometimes slip and use 'a' before a vowel sound, particularly if there is a pause between the article and noun; this includes native speakers, so it’s probably not worth correcting if it’s a slip. Correct in writing.

Students with languages that lack articles, such as Chinese and Russian speakers, will often drop articles because of L1 interference.