difference between -able and -ible


Defendable and Defensible, for instance; why are the endings spelt differently, thus? Is there a simple rule that is eluding me, please?

ending Suffixes asked Jun 14 '13 at 10:36 Pauli Murphy New member

2 answers


In Standard English, "defensible" and "defendable" are virtually synonymous  but defendable is more often used to describe a physical position (as in a fort or on a chessboard) whereas defensible is more used of arguments, theories etc.

Your two  words illustrate the general rule: where the root is a word that stands alone,  like defend or comfort, it is followed by able.  But if the root is not a word, like defens, illeg or incred, it is followed by ible.

link comment answered Jun 14 '13 at 14:06 Michael Cranfield Expert

They both mean the same thing, but you can tack "able" onto any word to make a new one without a hyphen. However, "ible" can't be added to make a new word, because there is already a set number of words that already have "ible" as part of the word. I found this rule on "English Club" website:

"Rule of thumb This rule can help you decide the correct spelling. It works most (but not all!) of the time. Remember, if you are not sure about a word, it is probably best to use a dictionary. Here is the rule: •If you remove -able from a word, you are left with a complete word. •If you remove -ible from a word, you are not left with a complete word (note that accessible, contemptible, digestible, flexible and suggestible above are among the exceptions to this rule)."

link comment answered Jun 14 '13 at 14:06 Star New member

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