The title tells the story! As an English learner I noticed that some words consisting the "sub" are sometimes pronounced slightly different. For example according to the Merriam-Webster (American accent) in these two words "subsidy" and "subsidiary" you can notice the differences, just click on the words! The guy says the "sub" part in the "subsidy" with a long a like vowel sound with this phonetic /sʌb/, but when it comes with "subsidiary" you can hear it as ə, the schwa sound! Why? Is there any rule(s) or something?

  • 4
    The difference could just be a result of which syllable of the word is stressed. In 'subsidy', it's the first (SUB-si-dy), while in 'subsidiary' it's the second (sub-SI-di-a-ry). Unstressed vowels tend to turn into the 'schwa' sound. Commented May 6, 2023 at 20:52
  • 1
    @QuackE.Duck Both words have the schwa sound; American English generally doesn't have a separate /ʌ/ sound. It's just a matter of stress.
    – alphabet
    Commented May 6, 2023 at 21:23
  • 11
    As a native BrE speaker I can hear no difference when I pronounce the two words. I suggest that it may depend on the speaker, their particular accent and possibly the surrounding words. Commented May 7, 2023 at 1:02
  • Edited on the assumption you meant "prefixes" rather than "pronouns". Commented May 7, 2023 at 23:32
  • strictly speaking, "sub" is not a prefix in these words. It is just the initial syllable.
    – Llaves
    Commented May 8, 2023 at 17:55

1 Answer 1


The general rule you're looking for is that the vowels in stressed syllables are pronounced as you'd expect (in this case /ʌ/), and vowels in unstressed syllables are pronounced reduced. About 90% of vowels reduce to a schwa when unstressed.

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