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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?

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  • 4
    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 brings up some good points about how pronouncing infinite with a hard "i" sound is difficult.
    – DJMcMayhem
    May 9 '15 at 7:45
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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.) May 9 '15 at 20:46
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    @James you misspelled per se. I wouldn't normally be quite this picky, but this is English Language Learners, after all.
    – phoog
    Sep 7 '20 at 18:25
  • "finite rhymes with 'my time'". Now I'm really confused. Oct 29 '20 at 3:22
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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.

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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 [[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

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