Why do we have two versions of the indefinite article? When did this happen? Are there any texts where only one is used?

  • This is a purely sandhi effect. It is automatic and implicit in correct speech. Your mouth just does it, exactly the same as it chooses alternate ways to say the definite article the under different phonetic environments — which are the same ones as determine how to pronounce a and an.
    – tchrist
    Commented Mar 21, 2015 at 17:59
  • It takes more effort to use one or the other all the time than it does to use them in the usual fashion. People are inherently lazy.
    – Hot Licks
    Commented Mar 21, 2015 at 18:16
  • 2
    For the same reason we have two versions of the definite article. Sandhi, as @tchrist points out, following precisely the same rule, in precisely the same environments. Commented Mar 21, 2015 at 18:19
  • 1
    In Old English, there was no indefinite article. In Middle English, the indefinite article was an (descended from the Old English word for one, which was an). By Shakespeare's time, the 'n' was being dropped before consonants. Commented Mar 21, 2015 at 18:19
  • Related: Was “an unicorn” ever correct?
    – herisson
    Commented Jun 30, 2017 at 8:37

1 Answer 1


The following extract may help understand the origin and evolution of a and an ( see also the juncture loss below).

Indefinite article:

  • The indefinite article of English takes the two forms a and an. Semantically they can be regarded as meaning "one", usually without emphasis. They can be used only with singular countable nouns; for the possible use of some (or any) as an equivalent with plural and uncountable nouns.

  • Distinction between a and an:

  • The form an is used before words starting with a vowel sound, regardless of whether the word begins with a vowel letter. This avoids the glottal stop (momentary silent pause) that would otherwise be required between a and a following vowel sound. Where the next word begins with a consonant sound, a is used. Examples: a box; an apple; an SSO (pronounced "es-es-oh"); a HEPA filter (HEPA is pronounced as a word rather than as letters); an hour (the h is silent); a one-armed bandit (pronounced "won..."); an heir (pronounced "air"); a unicorn (pronounced "yoo-"); an herb in American English (where the h is silent), but a herb in British English.


  • Both a and an are usually pronounced with a schwa: /ə/, /ən/. However, when stressed (which is rare in ordinary speech), they are normally pronounced respectively as /eɪ/ (to rhyme with day) and /æn/ (to rhyme with pan). See Weak and strong forms in English.


  • An is the older form (related to one, cognate to German ein; etc.). An was originally an unstressed form of the number ān 'one'.

Juncture loss:

  • In a process called juncture loss, the n has wandered back and forth between the indefinite article and words beginning with vowels over the history of the language, where for example what was once a nuncle is now an uncle.

  • The Oxford English Dictionary gives such examples as “smot hym on the hede with a nege tool” from 1448 for “smote him on the head with an edge tool”, as well as “a nox“ for an ox and “a napple“ for an apple. Sometimes the change has been permanent. For example, a newt was once “an ewt“ (earlier euft and eft), a nickname was once “an eke-name”, where eke means "extra" (as in eke out meaning "add to"), and in the other direction, “a napron” (meaning a little tablecloth, related to the word napkin) became an apron, and “a naddre” became an adder. The initial n in orange was also dropped through juncture loss, but this happened before the word was borrowed into English.

(English articles: Wikipedia)

  • +1, particularly for 'nickname' in the 'Juncture loss' section. Would you mind editing in the link to the wikipedia article?
    – Lawrence
    Commented Mar 14, 2017 at 0:18
  • @Lawrence done, I had forgotten about this answer until I had to do some personal research about silent H's in English. The Wikipedia article is very useful and interesting. Thank you Josh for finding it!
    – Mari-Lou A
    Commented Jun 30, 2017 at 6:38

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