"A" and "an" function

"A" and "an" function as the indefinite forms of the grammatical article in the English language and can also represent the number one. An is the older form (related to one, cognate to German ein; etc.), now used before words starting with a vowel sound, regardless of whether the word begins with a vowel letter.[8] Examples: a light-water reactor; a sanitary sewer overflow; an SSO; a HEPA filter (because HEPA is pronounced as a word rather than as letters); an hour; a ewe; a one-armed bandit; an heir; a unicorn (begins with 'yu', a consonant sound).

Juncture loss

In a process called juncture loss, the n has wandered back and forth between words beginning with vowels over the history of the language, where sometimes it would be a nuncle and 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 and 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" became "an apron" and "a naddre" became "an adder." "Napron" itself meant "little tablecloth" and is related to the word "napkin". An oft-cited[citation needed] but inaccurate example is an orange: despite what is often claimed, English never used a norange. Although the initial n was in fact lost through juncture loss, this happened before the word was borrowed in English (see orange (word)).

Discrimination between a and an

The choice of "a" or "an" is determined by phonetic rules rather than by spelling convention. "An" is employed in speech to remove the awkward glottal stop (momentary silent pause) that is otherwise required between "a" and a following word. For example, "an X-ray" is less awkward to pronounce than "a X-ray," which has a glottal stop between "a" and "X-ray". The following paragraphs are spelling rules for "an" that can be used if the phonetic rule is not understood.

The form "an" is always prescribed before words beginning with a silent h, such as "honorable", "heir", "hour", and, in American English, "herb".[9] Some British dialects (for example, Cockney) silence all initial h's (h-dropping) and so employ "an" all the time: e.g., "an 'elmet". The article "an" is sometimes seen in such phrases as "an historic", "an heroic" and "an hotel of excellence" in both British and American usage, although usually violating the phonetic rule in such cases.[9] Merriam-Webster's Dictionary of English Usage allows "both a and an are used in writing a historic an historic".

An analogous distinction to that of "a" and "an" was once present for possessive determiners as well. For example, "my" and "thy" became "mine" and "thine" before a vowel, as in "mine eyes". This usage is now largely obsolete.

The appearance of an or a in front of words beginning with h is not limited to stress. Sometimes there is a historical root as well. Words that may have had a route into English via French (where no hs are pronounced) may have an to avoid an unusual pronunciation. This never applied to words of Germanic origin, as the hs would be pronounced and a used.[9] Further, some words starting with vowels may have a preceding a because they are pronounced as if beginning with an initial consonant. "Ewe" and "user" have a preceding a because they are pronounced with an initial y consonant sound. "One-eyed pirate" also has a preceding a because it is pronounced with an initial w consonant sound. Pronunciation of a and an

Usually a is pronounced as a schwa: /ə/. However, when the meaning of indefiniteness is combined with the meaning as the quantifier "one", the latter can be emphasized by pronouncing a as the so-called long a: /eɪ/.

Usually an is pronounced to rhyme with "Stan", as /æn/. However, in rapid speech the vowel is often degraded to a schwa: /ən/.

Representing the number one

In addition to serving as an article, a and an are also used as synonyms for the number one, as in "make a wish", "a hundred". An was originally an unstressed form of the number ān 'one'.

A and an are also used to express a proportional relationship, such as "a dollar a day" or "$150 an ounce" or "A Mars a day helps you work, rest and play", although historically this use of "a" and "an" does not come from the same word as the articles.[12]

The mathematically-minded might heed H. S. Wall's reminder that the statement "I have a son" does not necessarily imply that "I have exactly one son" or that "I have only sons". In other words, "The little words count."

"Some" as an indefinite article
As a plural

The word some is used as a functional plural of a/an. "An apple" always means one indefinite apple. "Give me some apples" indicates more than one is desired but without specifying a quantity. This finds comparison in Spanish, where the singular indefinite article 'uno/una' ("one") is completely indistinguishable from the unit number, but where it has a plural form ('unos/unas'): Dame una manzana" ("Give me an apple") > "Dame unas manzanas" ("Give me some apples").

However, some also serves as a quantifier rather than as a plural article, as in "There are some apples there, but not many." As a result, the meaning intended by the speaker may be unintentionally or even deliberately unclear, or the speaker could intend both meanings simultaneously: "I see some cars" could have the indefinite meaning in "I see some cars (but I don't know whose)" or the quantificational meaning in "I see some cars (but not a lot of them)".

As a singular

Some also serves as a singular indefinite article, as in "There is some person on the porch". This usage differs from the usage of a(n) in that some indicates that the identity of the noun is unknown to both the listener and the speaker, while a(n) indicates that the identity is unknown to the listener without specifying whether or not it is known to the speaker. Thus There is some person on the porch indicates indefiniteness to both the listener and the speaker, while There is a person on the porch indicates indefiniteness to the listener but gives no information as to whether the speaker knows the person's identity.

However, some before a mass noun (a singular noun referring to a non-discrete undivided entity) always has a partitive meaning: for example, in I'll have some coffee, some means a subset of all coffee.

Similarities in other languages

Yiddish, another Germanic language, also employs "a" (אַ) and "an" (אַן) in essentially the same manner.

In Hungarian, a and az are used the same way, except that in Hungarian, a(z) is the definite article. Juncture loss occurred in this case as well, since az was the only article in use in 16th century Hungarian (e.g. in the poetry of Bálint Balassa).

In Greek and Sanskrit, a- and an-, meaning "not" or "without", are root words, cognate with Latin in- (when used as a negative) and English un-, meaning without.

Italian has many articles (8 + juncture loss) basically expressing the same ideas of definite and indefinite as English ones. The article the corresponds to il, lo, la, i, gli or le indifferently (remembering that Italian has masculine and feminine nouns, so that it is not indifferent to join any one of those articles with any Italian noun, indiscriminately) and the English articles a / an corresponds to Italian un or una (again, the masculine / feminine distinction must be taken into account). Moreover, no geographical rule applies to any of the Italian articles corresponding to the article the, so that, for example, it is correct to say la Germania which means Germany, in English.