In the following example, is it appropriate to use a or an as the indefinite article, and why?
He ate __ green apple.
I know that in the case of just "apple", it would be "an apple," but I've heard conflicting answers for "green apple," where the noun is separated from the article by an adjective.
Also, which is more appropriate in this case:
He ate __ enormous Pop-Tart.
The question of "a" vs "an" is always decided by the pronunciation of the word that follows the article. Thus, various geographical regions that have different pronunciation rules may use a different article for the same word.
Words that begin with a vowel sound, such as "apple", "egg", or "hour" are preceded by "an".
All other words, such as "cake", "pie", and "user" (which begins with a y sound), are preceded by "a".
Except (as lifted from @Nohat's comment below) - The rules before "h" are a little tricky, but clear: if a word begins with an "h" sound and the first syllable is stressed (like "house"), then it never takes "an". If the first syllable is not stressed (like "historical") then it is possible to use "an". Some usage authorities would say you must use "an" in those cases, but Nohat is not one of those authorities. You find both "a" and "an" used before words like "historical".
So to answer your actual question:
He ate a green apple.
He ate an enormous Pop-Tart.
"Green" does not begin with a vowel sound, so we use "a".
"Enormous", on the other hand, does begin with a vowel sound, so we use "an".
There is a bizarre urban legend of sorts that you're "supposed to" use "an" if the head noun in the noun phrase it determines begins with a vowel sound, rather than the first word in the noun phrase, giving rise to claims that "an green apple" is somehow "technically" correct. Here is a blog post of someone who seems to have gotten this idea. And here is the discussion on Language Log about that blog post.
In any case, the rule is that you use "an" if the next word begins with a vowel sound. Vowel sound is crucial here because many words that begin with vowel letters do not begin with vowel sounds (e.g. user) and vice versa (e.g. hour).
This makes it a kind of sandhi rule for "intrusive N" in English for indefinite articles, avoiding hiatus between the article and the following word.
As said, an before vowels and a otherwise. We know how/when, but not why.
According to Asudeh and Klein, the morpheme for the English indefinite determiner is represented by three different allomorphs ([ə], [ən], and [ej]—though I disagree with schwa slightly, it's the same in spirit), whose appearance is phonologically determined. When the morpheme is immediately followed by a segment marked by [+continuant], [ən] is selected, and if [-continuant], [ə]—the final form is uttered in isolation. —I question their use of [+continuant] instead of the traditional "vowel": this doesn't handle the the case of fricatives: *"an sister"; or approximates: [+continuant, +sonorant], *"an yacht".
What's really interesting here is that they mention a work by Harris that says that this is a form of deletion, that [ən] is the underlying form and deleted where the [n] cannot fill the onset of the following syllable. This begins to explain why a won't work before vowels (as well as why it is an before consonants).
Finally, it's interesting to know that this was a source of great debate for many years. A lot of people argued that this was anything but phonologically determined, wasting a ton of time and effort. Pay attention to phonology!
Have you really heard conflicting answers? I'm not aware of any controversy amongst native speakers on this issue.
a green apple
is correct.
This is decided by pronunciation, nothing more.
Similarly for the two pronuncations of "the" (ði: and ðǝ).
"He ate [insert here] enormous Pop-Tart."
"an" is correct here, it's decided by pronuncation of the following word, nothing more.
The only instance of a/an controversy amongst native speakers which I'm aware of is "a/an historical", with "an historical" plus aspirated "h" being preferred by some speakers.
Personally, I'm quite happy with waiwai's answer and many of the other points made here. However, one point not really addressed so far is why this rule is so.
The answer is fairly simple. For native english speakers, it's easier to physically say 'an apple' rather than 'a apple', 'an hour' rather than 'a hour'.
I'm sure speech therapists can explain technically in terms of phonation and resonance, but it's not my area of expertise.
It's understandable therefore, that some non-native English speakers might be puzzled - since their vocal chords may be trained differently.
Whether you use a and an for the indefinite article is always determined by the first sound (NOT the first letter!) of the very next word.
The grammatical role of that word in the noun phrase is irrelevant. Spelling is also completely irrelevant, except insofar as it relates to the pronunciation. Since English spelling often does not relate to pronunciation in a straightforward way, spelling is an unreliable guide to the use of a vs. an.
If you’re unsure of the pronunciation of a word or phrase, you can look it up in a dictionary that has a pronunciation guide. There are many good online dictionaries available for free; you can see a list of some of them at the following post: What good reference works on English are available?
The rule is simple, as long as you keep in mind the very important fact that it is based purely on pronunciation and never based on spelling. In modern standard English, we use a before words that start with consonant sounds when they are transcribed phonemically, and an before words that start with vowel sounds when they are transcribed phonemically.
As I said already, this has nothing to do with ordinary English spelling. You need to use your ears, or look at a phonemic transcription of the word (most of these are based on the International Phonetic Alphabet).
Some of the letters used in the transcription many be unfamiliar to you. If so, it may be helpful to view the lists of IPA letters and example words in the following lecture notes: The Vowels and Consonants of English, by Nigel Musk. If you've chosen to use a dictionary that uses a different system from the IPA, then you should look to see if it has a table of the sounds used in its transcription system where they are classified as consonants and vowels.
It's generally fairly intuitive, but keep in mind that the semivowel sounds /w/ (the “w” sound at the start of wing) and /j/ (the “y” sound at the start of year) count as consonant sounds for the purpose of this rule, despite their phonetic similarity to vowels. So we say "a wing" and "a year."
Here are some examples:
It is always acceptable to follow the rule described above and use a before words that start in pronunciation with the sound /h/, which is considered a consonant sound in English. (As always, be mindful of the distinction between spelling and pronunciation: some words spelled with "H", such as hour or honest, are never pronounced with /h/, and so we always use an in phrases like "an hour" or "an honest effort", because the words hour and honest start with vowel sounds.)
However, there is an optional exception. A number of style guides describe it as acceptable—but not mandatory—to use an before words that start with the consonant sound /h/ followed by an unstressed syllable, such as historical (stressed on the second syllable: "hi-STOR-ical"). That is, both "a historical" and "an historical" can be considered correct (although specific individuals may have more restrictive judgements). In contrast, my understanding is that words that start with the sound /h/ in a stressed syllable, such as history (stressed "HIS-tory"), are always used with the article a instead of an in standard present-day English. So only a can be used in "a history" (unless you pronounce the word without an /h/ sound). (It is possible to find historical examples of "an history"; for more on this, see below.)
The use of "an" before words like historical may have originally been an effect of speakers dropping the "h" sound before an unstressed vowel, but modern English speakers who use "an historical" and like phrases don't necessarily drop the /h/ sound entirely.
For more on this, see the answers to Why we say "an historical" but "a history" and When should I use "a" versus "an" in front of a word beginning with the letter h? (for the latter question, look at all the answers, not just the top ones, to get a complete picture).
See also the following Word Reference thread: A/an: historic, historian, historical, hotel, humanitarian, Hawaiian, honour, herb, hypothesis ...
Sometimes, you might hear people use "a" before a word that starts with a vowel sound, with a glottal stop in between the two vowel sounds. For example, someone might say "a apple" (/əˈʔæpl̩/). However, this is not standard, and is only common for some speakers. For other speakers, it might only occur as an occasional disfluency. In writing, the use of "a" before a word that starts with a vowel sound may reflect this phenomenon, but is often just an error resulting from edits that change word order or word choice. In either case, writing a before a word that starts with a vowel sound is non-standard.
In earlier stages of English, these articles were not always distributed in the same way as they are now. This is partly because people used to pronounce some words with different sounds. Be aware of this if you're reading an old text, such as the King James Bible.
See the following questions for more information:
Another good resource on this topic is the following blog post by waiwai93: Articles: “A” vs. “An”
The rule for using the article a versus an is exactly the same as the rule governing whether one pronounces the article the as /ðə/ or as /ði/.
Both rules operate for the same reason: they make it easier to pronounce and understand an article as distinct from the NP following it. If that NP starts with a vowel sound, we change the article’s pronunciation.
If you did it the wrong way, the article would collide with what came afterwards.
It is the same with the, but here it is reflected in pronunciation alone.
If you do either article the wrong way, they will get lost in speech, which will make things harder to understand.
Language is most easily spoken and listened to when there is an alternating pattern between consonants and vowels. It's very easy for the ear to distinguish between vowels and consonants, but not so easy when they are clumped together.
An easily spoken sentence would look like this:
vowel consonant vowel consonant vowel consonant vowel consonant vowel consonant
To maintain this pattern while using an indefinite article, it's necessary to insert a consonant (n) between two vowel sounds or remove the n between a vowel and consonant, whichever way you prefer to view it.
An apple is easier to speak and hear than a apple. A bear is easier to speak and hear than an bear. An IBM employee is easier to speak and hear than a IBM employee.
Some regional dialects actually do not pronounce their "h", such as British English. In those regions, it's easier to speak and hear "an historic event" than "a historic event".
"an" before vowels, and "a" before everything else.
Except for a few exceptions...
Words that begin with a consonant, but sound like they begin with a vowel, I've always understood them to be proceeded by "an" since they begin with a soft sound (eg - An heirloom).
As already pointed out by another answer, "user" starts with a vowel, yet is preceded by "a" because it begins with a hard sound.
https://owl.english.purdue.edu/owl/resource/591/01/ helped substantially, from which I abtract:
How do you know when to use the indefinite articles?
The choice of article is actually based upon the phonetic (sound) quality of the first letter in a word, not on the orthographic (written) representation of the letter. If the first letter makes a vowel-type sound, you use "an"; if the first letter would make a consonant-type sound, you use "a." However, you may follow these basic rules when deciding to use "a" or "an," remembering that there are some exceptions to the rules.
"A" goes before words that begin with consonants.
"An" goes before words that begin with vowels:
Exceptions
Use "an" before unsounded "h." Because the "h" hasn't any phonetic representation and has no audible sound, the sound that follows the article is a vowel; consequently, an is used.
When "u" makes the same sound as the "y" in "you," or "o" makes the same sound as "w" in "won," then a is used. The word-initial "y" sound ("unicorn") is actually a glide [j] phonetically, which has consonantal properties; consequently, it is treated as a consonant, requiring "a."
In addition to the answers here, consider this non-trivial example - (from Life, the Universe and Everything by Douglas Adams):
"I think, that there's an SEP over there"
Now here "a SEP" would do as well, but then you would have to pronounce it "sep" instead of "es-ee-pee" which is what the author meant. E, in "es" is a vowel.
Another less trivial example is "an hour". 'h' is a valid and pronounced consonant, but it still doesn't count.
It depends on the sound of the word following the article. If the following word has a vowel sound, use an. If the word has a consonant sound, use an a.
See Purdue Notes
There are a few exceptions to this.
If a vowel SOUND (a, e, o, i) follows, bar y & u, "an" MUST be used, as shown in the examples below:--
An array of delicacies. An enormous man. An Iraqi citizen. An obscure location.
But don't be fooled: if the word following "an" begins with a CONSONANT sound, u & y included here, "a" must be used, instead. Like this:--
A utopia of the present. A yearning. A black man of benevolence. A zebra from Africa.
So in summary, if a word that is immediately after a/an has a vowel sound, "an" must be used; if a word that is immediately after a/an has a consonant sound (which includes the sound y, which is taken on by the letters u & y), "a" is to be used.
Tip: regard the sounds rather than the letters when determining which to use. Soon, it'll come naturally.
Despite all the answers, for some people (regions?) it is normal to say:
a apple
a English
a enormous
a emotional
And so forth.
This usage produces a glottal stop between the 'a' and the vowel sound beginning the second word.
I think it would be helpful to review vowels and consonants according to their phonological definitions as opposed to their orthographical definitions (vowels:a,e,i,o,u, and sometimes y that most people think of). This will help clear any doubt when one says "if it starts with a vowel, use an, otherwise if it starts with consonant, use a".
vowel: etymologically related to Latin vocalis via the Old French voieul meaning "vocal" or "voice"
consonant: a compound of two morphemes, con (with) + sonant/sonans (sounding) Latin sonans via Greek σύμφωνον.
So as you see, the rules are fine. Pronunciation is key here, not orthography (how you write it). This explains the differences some people have. People pronounce things differently.
As I studied the origins of grammar in the 18c, I came to understand that most English grammars originated with classical (Greek and Latin) scholars, who attempted to shoehorn English into similar grammatical patterns (declensions, conjugations, mood, tense, voice, number, gender, etc.). One sticking point was to define what is a consonant, what a vowel. Their definition: a consonant sound is made using the lips and teeth and tongue; a vowel sound is made primarily with the breath. So, what to do with the aspirant "h"? The sound made when "h" begins a word is not made with the lips/tongue/teeth, but rather by a modification of the shaping of the breath when pronouncing the following vowel. So, "history" is sounded in the same way as you sound the following vowel "i", but slightly constricted to indicate the preceding "h" (that is, if you sound the "h" at all). Since "h" sometimes seems more like a vowel than a consonant, the choice of indefinite article must conform to that uncertainty: "a" before a stressed first syllable word beginning with "h" (an hisTORic occasion), but "a" before one unstressed (a HIStory), based on the belief that the "h" (breathy) sound is more pronounced when the syllable is stressed.
However, over time (as an ngram shows), "a historic" and "an historic" have gone in and out of usage for 300 years, so either one is now acceptable. Otherwise, in Standard English, "a" before consonant sounds, "an" before vowel sounds
Such choices were borne home to me when I had a student named "Yvonne". When I called on her, I pronounced her name "E-von"; she quickly corrected me: "My name is pronounced 'WY-von'." Which is, I take it, a Southern thing. Of course, I adhered to her preference. And I note: You might encounter an "E-von" or you might meet a "WY-von" in certain places, so choose your articles carefully.
Useful examination of this question in the field of linguistics: https://specgram.com/PsQ.XVI.4/06.pulju.indefinite.html
I'm proud and pleased to be obsessed with the minutiae of language.
I am raising my hand here...
To point out on the other side of the Atlantic the English always say, and even write as "an herbal tea"
I mean a herb [a hɜːb]; a is neutral, and h is aspirated; [eɪ hɜːb] when a is emphatic.
Go figure RP!
