Difference between -able and -ible

There are many things to be learned in the English language. There are many complicated principles regarding the proper use of prefixes and suffixes. In connection to the latter, there are two suffixes that are usually confused with each other. These are the suffixes ‘able’ and ‘ible.’

To those who are accustomed to English writing, distinguishing when to use one from the other is not a hard task to do. Once one gets used to it, one need not take note of the rules behind the usage. But for beginners, there are some rules to be followed in using the suffix ‘able’ and ‘ible’ with certain root words.

Rule 1 – If the root word seems to be a complete word in itself then it is safe to add the suffix ‘able.’

Rule 2 – In the case wherein the root word isn’t a completely spelled word then use the suffix ‘ible.’

These rules can best be shown in the following examples. In the word ‘acceptable,’ one uses the suffix ‘able’ because the word ‘accept’ as the root word is a completely spelled word. Hence, it is inappropriate if one uses ‘ible’ like ‘acceptible.’ For the second rule, the word ‘compatible’ uses the suffix ‘ible’ because the root word ‘compat’ is not a complete word. That’s why it will also be inappropriate to use the suffix ‘able’ to ‘compat’ making the final word into ‘compatable.’

Rule 3 – Nevertheless, if the root word ends in the letter ‘e’ then drop that letter first before adding ‘able’ as in the case of the word ‘advise’ that becomes ‘advisable.’

It is also said that the suffix ‘ible’ is used for words that have a Latin root or origin. It is estimated that there are about 180 words that have the suffix ‘ible.’ Some of the most common examples of words that make use of ‘ible’ are: accessible, audible, combustible, comprehensible, irreversible and many more.

The suffix ‘able’ can also be attached to words with a Latin root but only in rare occasions. This is true in the case of the word ‘depend’ and making it into ‘dependable.’ Depend is actually taken from the Latin word ‘dependere’ that means ‘to hang down.’ Conversely, the suffix ‘able’ is more aptly attached to root words of non-Latin root like washable and affordable.

However, one should also take note that there are some exceptions to this rule. The words access, contempt, digest, flex, and suggest are best connected to the suffix ‘ible’ even if these terms are complete root words. Hence these will become accessible, digestible, suggestible, flexible and contemptible. There are still other exceptions not listed here.

Summary

1. The suffix ‘able’ is attached to complete root words while ‘ible’ is generally connected to incomplete root words.

2. The suffix ‘able’ is usually attached to root words that are non-Latin in origin whereas ‘ible’ is usually used with words of Latin nature.