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  1. #1

    Question -able or -ible?

    Can anyone tell me why some adjectives have -able as a suffix, while others have -ible? Does it have anything to do with the word's etymology?

  2. Casiopea's Avatar

    • Join Date: Sep 2003
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    Re: -able or -ible?

    Most of the -able words were borrowed from French, and most of the -ible words were borrowed from Latin. Click on the link below to read more.

  3. #3

    Re: -able or -ible?

    Thanks very much. It's as I thought. I've now got Bart in my favourites!

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    Re: -able or -ible?

    When to Add -ible and When to Add -able
    Here's a tricky question for you:

    Why do some words add the suffix -ible and others -able?

    Why indeed.

    A good rule of thumb is that if the root word is a complete word, you add -able
    e.g. accept - acceptable; laugh - laughable; suit - suitable and so on.

    If the word ends in y, change it to i e.g. justify - justifiable, and if it ends in e, you usually (but not always) drop the e.
    e.g. believe - believable.

    But ... if the consonant preceding that vowel is a g or a c, you keep the e. If you don't, the consonant would become hard, and the word would sound odd.
    e.g. notice - noticeable; knowledge - knowledgeable.

    And, if removing the e would change the pronunciation of the preceding vowel then you leave the e.
    e.g. like (long i) - likeable; sale (long a) - saleable.

    If the root is an incomplete word, you add -ible
    e.g. vis- visible; tang- tangible; cred - credible.

    Remember this by the two i's: Incomplete -ible.

    That's a pretty easy way to work it out, don't you think? You'll find more helpful writing tips at

    • Join Date: Aug 2006
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    Re: -able or -ible?


    I'm not sure if that rule really works as I found this website looking for a rule due to a question about 'deductible' - deduct is also a complete word. Maybe the Latin and French bit helps though....


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