I am curious, why does "vacuum" have two "u's?" I am aware that it is a Latin-derived-Word, so therefore it was probably pronounced [wakwum], logically. Is this correct? I can understand us English speakers maintaining the original spelling, and then pronouncing it as any of: [vacym~vakym~vacjum~vakjum~vacjʌm], because of our willingness to preserve the original spelling*, but why do other languages maintain the the two "u's" also? Or, because I am unaware of Latin spelling, was it pronounced: [wakuːm] or potentially [wakwuːm].

*for instance, how words that maintained "-tjon (-tion)" like "Nation." We opted to continue to spell them "natjon~nation" for preservation of the original spelling, and keep saying [naˑsjon~nasjon], rather than spelling it "nacion," as some languages opted, to preserve the hint of the words' latin origins.

  • I don't know of any English speaker that pronounces nation as "[naˑsjon~nasjon]," if you're using the IPA. If you're not using IPA, what kind of phonetic transcription are you using? Apr 6, 2017 at 22:41
  • The pronunciation part of your question seems to be language-specific. Also, the section part (about "-tion") seems to be a separate question since it has nothing to do with "vacuum". Could you clarify the question a bit? Apr 6, 2017 at 23:34
  • No, that was referring back to when they were first standardizing the english spelling almost 400 years ago. That was a reference to the debates then. That was I.P.A. From Latin to contemporary english: [natjon→nasjon→neˑʃʌn]. Apr 7, 2017 at 1:31

1 Answer 1


The Latin vacuum is the nominative neuter singular form of the adjective vacuus 'empty'. Both words had and still have three syllables each, that is, both Us are pronounced as separate vowels, and yes, both words have hiatus. That is why the transcription of vacuum in Classical Latin is:

vacuum /ˈwa.ku.um/, [ˈwa.kʊ.ʊm]

The reason why there are two Us is that the word is formed from the verb vacō (“I am empty, void”) +‎ -uus (“adjective-forming suffix”).

  • I've never heard it pronounced with three syllables. I would say VAK-yoom. But maybe that's what you meant about the "hiatus".
    – Clonkex
    Apr 7, 2017 at 1:51
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    @Clonkex: Yellow Sky is saying that the Latin word "vacuum" has three syllables. (The "had and still have" wording is presumably intended to cover both the historical forms of Latin that various other languages borrowed the word from and present-day forms of Latin that are still spoken.) By "hiatus" (s)he means that the two U's are adjacent vowels in separate syllables.
    – ruakh
    Apr 7, 2017 at 3:22
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    @Clonkex - ruakh is absolutely right, I explained the pronunciation of the word in Latin and also I explained why there are 2 u's there. If your question was about the English pronunciation of "vacuum", you 1) haven't formulated your question clearly; 2) you asked it on a wrong StackExchange, here we speak about linguistics, not about English; 3) if you need the English pronunciation, you can look it up in any dictionary, nowadays they all have transcription, and most of them have playable audiofiles to illustrate the pronunciation.
    – Yellow Sky
    Apr 7, 2017 at 3:29
  • @YellowSky What question? I was just commenting on the fact that I thought you were saying in modern day English it would be pronounced with three syllables, but ruakh correct me on that. If you confused me for the OP, good job lol :P
    – Clonkex
    Apr 7, 2017 at 3:52
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    I have reposed the question here: latin.stackexchange.com/questions/3054/…
    – fdb
    Apr 8, 2017 at 11:52

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