Indefinite article

An indefinite article is a grammatical article used to express indefiniteness (i.e. lack of definiteness). In English, there are two of these; a and an. They provide a grammatical marker that the following noun is both (1) countable and (2) singular.

Contrast the definite article.

Form

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 So, this is superseded by: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.

Pedagogy

The indefinite articles are introduced at beginner level. The meaning can be explained simply; “a means one.”

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.