I was asking this question on Area 51: "How do I tell if an airport scanner is a X-ray scanner?", but I keep wanting to put an 'an' in front of X-ray because it starts with the 'eh' sound.

So is it 'a' or 'an'?

  • possible duplicate of When should I use "a" vs "an"? Dec 27, 2011 at 16:34
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    An x. (grammar.quickanddirtytips.com/a-versus-an.aspx)
    – JLG
    May 31, 2012 at 1:53
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    You can’t say “*a ex”. Check with your ex-wife: isn’t she an ex? Surely!
    – tchrist
    May 31, 2012 at 4:03
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    The rule for a/an refers to the sound they precede. If it's a vowel sound, you say an; if it's a consonant, you say a. The name of the letter X is pronounced /ɛks/, and /ɛ/ is a vowel, so it's always an 'x', but a 'y' (/way/) and a 'z' (/zi/); /w/ and /z/ are consonants. Jan 26, 2014 at 19:08

6 Answers 6


Definitely "an". The word X-ray is never pronounced any way other than "exray", and as has been discussed before, the choice of a or an is based solely on pronunciation, regardless of spelling. Since X-ray is pronounced beginning with a vowel, it must be preceded by an.

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    thus, isn't it true that you use either "an" or "a" in connotation, when using them with a noun that begins with "h"? Many people misuse the an, i.e., "an heart" is incorrect, but many people falsely believe that one must always use "an" with h. Thanks
    – kalaracey
    Jan 7, 2011 at 23:44

'an', because how it sounds is what matters.

An interesting example is an hour, et. al. The fact that h is not considered a vowel from the article point of view says a lot about English pronunciation.

Another interesting example of article form leaking unusual information, from Life, the Universe and Everything:

"I think," said Ford in a tone of voice which Arthur by now recognized as one which presaged something utterly unintelligible, "that there's an SEP over there."

It means that the author meant that SEP achronym is to be pronounced 'es ee pee' and never 'sep'.


In this situation you use "an", because phonetically the sound you are making (the X) starts with an "E": you hear "Ex - ray".

This is true of any letter that, when pronounced, sounds like it starts with a vowel, and often you will need to adapt your use of "a" or "an" even for the same letter.

For example:

A Nasty cold was going around the office


An NHS doctor was the first to diagnose the bug

Phonetically you say "EN AITCH ESS", so you use "An NHS". Likewise, as you say "EX-RAY", you say, "An X-Ray".

The way the word is pronounced is the key factor here, rather than the spelling.

Edit: Looks like JSBangs beat me to it :)


"An X" is correct, as the pronunciation of the letter X has an initial vowel sound.


The choice of the indefinite article in English is purely phonetically based. Since the pronunciation of the letter X is headed by a vowel, an is the natural choice.


I do not thinks Phonetics has any bearing on "A" or "AN". When I studied the language a Thousand years ago, the rule was a consonant requires "A", a vowel requires "AN". That was the rule, and a rule is a rule, not an elephant. The english language is a living, ever changing beast and has more exceptions to a rule than it has rules. I have heard it said that "The only other language with more exceptions than english, is mandarin chinese ."

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    A consonant sound requires "a" before it, and a vowel sound requires "an" before it. The problem is that the spelling of words doesn't always tell you the sound that the word starts with. Why you do think we write "an hour" and "a used car"?
    – Kosmonaut
    Jan 8, 2011 at 2:36
  • This is what I was taught by many teachers, as an absolute, a for consonants except H, an for H and the vowels. When I speak, the phonetic approach described elsewhere on this page is what occurs naturally.
    – Orbling
    Jan 8, 2011 at 5:07
  • @Orbling: The phonetic rule is, for all intents and purposes, absolute. The "h" part does not pattern the same in all dialects. In my school in the US, there was no "h" part of the rule.
    – Kosmonaut
    Jan 9, 2011 at 3:11
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    @Orbling: In (traditional) Received Pronunciation, the rule is "a" before an "h" sound that occurs in a stressed syllable, but "an" before an "h" in an unstressed syllable - thus, "a history" (because the stress is on HIStory), but "an historian" (because the first syllable is unstressed: hisTORian). However, it is much more common these days to use "a" with both. The same rule applies in writing and speaking; there is no different rule "a/an" for writing - if you want your writing to appear educated, write "a/an" as if speaking in an accend that sounds educated :-)
    – psmears
    Jan 9, 2011 at 16:57
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    So what are you saying? Is there a rule to follow here, or is there an exception to a rule? What you wrote has elicited some commentary, but it doesn't respond to the question. Apr 27, 2012 at 16:19

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