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Finite rhymes with 'my time'. Infinite rhymes with 'minute' (as in seconds, minutes, hours and not minute, micro, small).

Why are i's in finite and infinite pronounced differently?

Void
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aarbee
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    I don't think there is a **rule** per say. There are some other words that change pronunciation when you add a prefix/suffix, such as famous and infamous, or photograph and photographer. [This Q&A](http://english.stackexchange.com/questions/8218/pronunciation-differences-between-finite-and-infinite) brings up some good points about how pronouncing infinite with a hard "i" sound is difficult. – DJMcMayhem May 09 '15 at 07:45
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    I'm voting to close this question as off-topic because in my opinion, asking how come a word is pronounce the way it's pronounced is about etymology and etymology is off-topic on ELL. (And migrating this question to ELU would make it a duplicate.) – Damkerng T. May 09 '15 at 20:46
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    @James you misspelled *per se.* I wouldn't normally be quite this picky, but this is [Ell.SE], after all. – phoog Sep 07 '20 at 18:25
  • "finite rhymes with 'my time'". Now I'm really confused. – Eric Duminil Oct 29 '20 at 03:22

1 Answers1

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Finite is pronounced ['faɪnaɪt] while infinite is pronounced [ˈɪnfɪnɪt]. So why is the vowel in the first syllable of 'finite' different from the vowel in the second syllable of 'infinite'?

OK, it's not because of Trisyllabic Laxing, I made an erroneous assumption which I deeply regret.

The answer is actually simple. As Luigi Burzio explains in Principles of English stress, the reason boils down to English stress patterns.

The diphthong [aɪ] (as in bite) almost never occurs in unstressed syllable. The diphthong [aɪ] has a systematic relationship with the short vowel [ɪ]. This relationship is also reflected in Trisyllabic Laxing; divine-divinity, derive-derivative and in drive-driven etc.

From this relationship, we can infer a general rule of thumb that [aɪ] will only occur in stressed syllables and when that syllable gets unstressed, [aɪ] will shorten to [ɪ].

Now when you prepend the prefix in- to finite, the primary stress moves to the prefix in- because it's a stress-bearing affix.

  • In + f[aɪ]nite → inf[ɪ]nite
  • In + p[əʊ]tent → imp[ə]tent
  • In + m[aɪ]grant → imm[ɪ]grant
  • In + f[eɪ]mous → inf[ə]mous

Another example would be cycle-bicycle:

  • Bi + c[aɪ]cle → bic[ɪ]cle

There are exceptions, however. Luigi Burzio has explained all the rules and exceptions thoroughly in his book. One of the many exceptions is the prefix un- which doesn't take primary stress, for instance, unab[eɪ]ted.

Latinate words in English tend to be stressed on the penultimate (second last) syllable unless that syllable is short, in which case the primary stress falls on the antepenult (third last syllable) but not on preantepenult (fourth last) as far as I know. That's why impossible, implausible, incredible etc., are stressed on the antepenult.

Void
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  • I thought of trisyllabic laxing (and that accounts for _infinity_) but it does not account for _finite/infinite_, as they both have just one syllable after the "fin". – Colin Fine Oct 12 '20 at 18:31
  • @ColinFine: Perhaps the primary stress is relevant here? – Void Oct 12 '20 at 18:32
  • Maybe. It's like _intimate_ (both verb and adjective) and _instigate_, but neither of those have a version without _in-_. I pronounce _indirect_ with /ʌɪ/ (it's usually somewhat reduced, but not to /ɪ/ - but the OED tells me that some people do use that pronunciation), but there is only secondary stress on the _in-_, not primary in that word. – Colin Fine Oct 12 '20 at 19:14
  • @ColinFine: After giving it some more thought... 'Infinite' comes from Latin *infīnītus* which was [pronounced](https://en.wiktionary.org/wiki/infinitus#Latin) [[ĩː.fiːˈniː.t̪ʊs]], stressed on the penult. But in English, we usually stress the antepenult, so something happened while borrowing it from Latin, though I'm not entirely sure (I don't know anything about Latin). Also compare 'potent' and 'impotent'. – Void Oct 14 '20 at 18:12
  • Re: "Now when you prepend the prefix *in-* to *finite*, the primary stress moves to the prefix *in-* because it's a stress-bearing affix": This doesn't seem to be consistent; consider "impossible", "implausible", "incorrigible", "inconceivable", "incredible", "invariably", . . . – ruakh Dec 10 '20 at 18:50
  • @Ruakh: I haven't read the entire book, but I think it depends on the number of syllables in the root word. If the root word is disyllabic and the prefix in- is added, the stress moves to the prefix. ...... English stress patterns are more complex than you might expect. – Void Dec 10 '20 at 18:54
  • @ruakh: It should be better now – Void Dec 11 '20 at 19:38