I just noticed that the word iron is pronounced EYE-URN in standard Englishes instead of what the spelling suggests. I have always been pronouncing it "EYE-RUN" but I just checked its pronunciation and it shocked me a bit.

So in UK English, it is /aɪən/ and in US English, it is /aɪrn/ according to the Cambridge Dictionary.

I know English spelling is not regular and as Ronald Sole said in a comment to my previous question, "Do not expect consistency in the pronunciation of any words in English. You can only look up words to find their provenance as a clue to pronunciation", but I just want to know the reason and cause for this.

Why is it pronounced as EYE-URN (IPA: /aɪən/ and /aɪrn/) but not EYE-RUN (/aɪrən/)?

  • 5
    Years ago I never heard anyone articulate the /r/ in iron. I first started noticing this on the Internet about 15-20 years ago - initially it mainly seemed to be confined to non-native speakers, but increasingly I hear it nowadays in the native Anglophone scientific community (where the difference between iron from ion might be highly significant, but not necessarily contextually obvious). Before that though, this "confusion" was only relevant in the context of making weak puns alluding to irony = like iron (there being no such thing as iony = like ions). Commented Oct 28, 2020 at 13:22
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    English spelling is fun, isn't it?
    – Void
    Commented Oct 29, 2020 at 2:12
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    Truly, this word should be pronounced as if Apple had started producing former US presidents/bad actors: iRon :-) Commented Oct 29, 2020 at 12:41
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    The "silent R" theory is very regional. Where I come from (Scotland) we prize Rs very highly and always give them the recognition they so richly deserve. If I were to go full Glaswegian on it, I'd pronounce element 26 as Eye-ah-rrun, with (count 'em) three syllables. Commented Oct 29, 2020 at 13:28
  • 5
    There's a certain irony here, with another very similar word pronunciation...
    – Tim
    Commented Oct 29, 2020 at 16:43

3 Answers 3



The pronunciation of 'iron' in standard varieties of English is EYE-URN (BrE: /'aɪən/, AmE: /'aɪrn/) and not EYE-RUN (which is also a common pronunciation of 'iron' in some varieties of English) because of a very common process called Metathesis. It's defined as the transposition/rearrangement of letters, syllables or phonemes (sounds) in a word.


There are some other words that show the same change; 'wasp' used to be waps, 'bird' used to be brid and 'horse' used to be hros, but they've changed over time. Why is that?

It's because of a very common process called Metathesis. /'aɪən/ is the metathesised version of (/'aɪrən/). 'Iron' commonly used to be pronounced the way it's spelt (/'aɪrən/), but due to metathesis, its pronunciation became EYE-URN (/'aɪən/). Other words such as horse, bird, third etc., reflect the change in spelling; however, 'iron' doesn't reflect that change probably because metathesis applied to it after the spelling was standardised.


Metathesis is defined as ’the transposition/rearrangement of letters, syllables or phonemes (sounds) in a word’.


  • 'wasp' used to be waps (wæps) [transposition of p and s]
  • 'bird' used to be brid [transposition of i and r]

{Historical Metathesis}

  • 'mix' being pronounced /mɪsk/ rather than /mɪks/ [transposition of k and s]

  • 'desk' being pronounced /dɛks/ rather than /dɛsk/ [transposition of k and s]

  • 'modern' being pronounced /'mɒdɹən/ instead of /ˈmɒd(ə)n/ (US: /ˈmɑː.dɚn/)

  • 'pattern' being pronounced /pætɹən/ instead of /ˈpæt.ən/ (US: /ˈpæɾ.ɚn/)

  • Another famous example from Shakespeare's 'The Tempest' is the figure of Caliban whose name originates from a phonological metathesis of /n/ and /l/ in 'cannibal'. [ThoughtCo]


Words having /r/ + vowel sequences are more susceptible to metathesis than others. According to A grammar of Old English Phonology by Richard Hogg, ‘R-metathesis normally occurs when /r/ is followed by a short vowel and a dental or alveolar consonant, usually /n/ or /s/’.

'Iron' is an example of /r/-metathesis. It was probably pronounced /'aɪrən/ (EYE-RUN) at one point, but it got metathesised to /'aɪərn/ (EYE-URN). However, the spelling remained unaffected.

Other examples of metathesis of /r/ include:

  • bird from brid (bridde)
  • third from thridde (ðridde)
  • horse from hros

The silent R in 'iron' in BrE

The reason why the r in 'iron' is absent in British English is because the r is followed by a consonant now (followed by /n/ in /'aɪərn/) and British English is non-rhotic, meaning the r is only pronounced when followed by a vowel. The same thing happened to 'bird', 'horse' and 'third' too (i.e. the r is followed by a consonant, so it's silent).

There are different types of metathesis, 'colonel' (pronounced KE(R)-NUHL /'kɜː(r)nl̩/) can also be said to be a product of metathesis. (See this answer on ELU for the spelling and pronunciation of 'colonel')

According to Wikipedia, the reason for ‘common speech errors’ is also metathesis.
Examples include:

  • perscription for prescription
  • interduce for introduce
  • revelant for relevant
  • foilage and foliage


  • 1
    @Void I believe you read the whole history and geography of this thing, before editing the whole answer altogether. I appreciate it. Not many answerers bother changing their answer to provide extra information, especially after their answer is accepted). I learned something new today. Thanks! (By the way, I would like to know, did you go and read The Tempest to find out the analogy?) Commented Oct 28, 2020 at 14:17
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    "Mix" is an interesting case, as the verb is a back formation from "mixed", which itself comes (ultimately) from Latin "mixtus", the past participle of "misceo", whose reconstructed Proto-Italic root is *miksko. It looks as though most forms of the Latin verb dropped the initial "k", while the participle dropped the second.
    – chepner
    Commented Oct 29, 2020 at 13:12
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    It might be useful to separate the examples which are almost entirely historical (wasp, bird, ask) from the ones which are common mistakes or regional variants (mix, desk, modern, pattern). I've never noticed anyone say "misk" or "deks", but have definitely heard "asterix" for "asterisk", which always amuses me as a fan of the comic strip character.
    – IMSoP
    Commented Oct 29, 2020 at 15:42
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    Little kids often transpose sounds in long, complicated words. Sometimes I find myself transposing letters when writing, possibly because of thinking in "future" letters and writing them ahead of their correct position. So... may be metathesis results from how brains "normally" work?
    – Pablo H
    Commented Oct 30, 2020 at 5:54
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    don't forget my favorite example of *hross -> hors -> horse Commented Oct 31, 2020 at 1:18

In some regional accents it is /aɪrən/, but this is rare enough in most regions that people may never have come across it and will consider it an error, so learners aren't advised to pronounce it that way.

In the 15th century, spelling variants included "irn".

According to the Oxford English Dictionary, the standard pronunciation shows "loss of the vowel of the second syllable and probably the development of a syllabic nasal... with subsequent loss of the syllabic quality of the nasal and development of a glide vowel between a diphthong and r, although the precise details are uncertain... Pronunciations not reflecting this development survive in regional varieties of English (Yorkshire and Scotland); compare Scottish Standard English /ˈaɪrən/."

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    Thank you for revealing the fact that regional accents preserve the "older" pronunciation. Just because they're rare doesn't mean they're absent.
    – Rich
    Commented Oct 29, 2020 at 20:31
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    I love this answer. It has a lot of explanatory power, and after reading it, the shift in pronunciation looks almost inevitable. Start with [aɪ rən]. Eventually, the n became syllabic, because that's an easy change that most English speakers wouldn't notice. This becomes [aɪr n̩]. Now the r is in the same syllable as the diphthong aɪ which is hard for a lot of English speakers to prounounce. It's normal to turn aɪr into two syllables as [aɪ ər n̩]. Suddenly there's no need for the syllabic n anymore and it turns into [aɪ ərn].
    – Jetpack
    Commented Oct 29, 2020 at 21:37
  • Thanks. It seemed plausible to me too, and the OED cites E. J. Dobson Eng. Pronunc. 1500–1700 (ed. 2, 1968) II. § 328A - although it seems to conflict with the (metathesis) theory in @Void's (excellent) answer (and since 1968 was a while back, it's possible Void's sources represent more recent scholarship).
    – rjpond
    Commented Oct 29, 2020 at 21:52
  • When sung as two syllables, [e.g. from In the Bleak Midwinter, "Earth stood hard as i-ron", at least to my ear, the "r" should occur earlier in the word than when spoken. Closer to "Eire un" than "I run" or "I earn", but many words shift pronunciation when sung, for a variety of reasons.
    – supercat
    Commented Nov 21, 2020 at 9:10
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    I'm late to the party, but anyway. About 20 years ago, I was on the bus from Denver to Boulder, Colorado, USA, and the driver called out a stop at the then-new shopping mall, Flatiron Crossing (so named for a local geological formation), saying, "Flut-eyerun Crew-wassing". I love accents and the driver's was very distinctive, it's not the way people generally talk in that area. I still wonder where he was from. Commented Jan 9, 2021 at 0:49

Personally, I think it's just a passed down thing from generation to generation. A butchering of the language so to speak. You can ask the same thing why "gross" isn't pronounced like "cross", or the why it's "Wendsday" and not "Wednesday", or why it's "i before e except after c" which is just weird.

  • 2
    Hi, and welcome to ELL. Please take the tour and consider how you might improve your answer. As it stands, this sounds like opinion. Can you quote and link to a source that shows this is a generally accepted explanation?
    – Davo
    Commented Oct 30, 2020 at 15:06
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    Isn't it "Wensday", almonst without any "d" sound? Commented Oct 30, 2020 at 18:03
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    '... "i before e except after c" which is just weird ...' - I see what you did there! Commented Feb 3, 2021 at 23:57

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