We previously did a post on words ending in ‘–ance’ and ‘–ence’. Another such pair of words is ‘–able’ and ‘–ible’. Words ending in these suffixes are adjectives that refer to the ‘ability to’ or ‘necessity to’. For example ‘acceptable’ or ‘possible’. The problem is in the difficulty to remember which ending to use, ‘-able’ or ‘-ible’. What makes it even more confusing is that the two are pronounced identically. So, when do use ‘-able’ and when do use ‘-ible’?
English being English, there is no rule; but generally, these hints work most of the time:
* Add ‘–able’ when the root word is a complete word. For example:
Accept + able = acceptable
Suit + able = suitable
Depend + able = dependable
* Add ‘–able’ when the root word ends in ‘e’, but first drop the ‘e’. For example:
Excuse – e + able = excusable
Value – e + able = valuable
Desire – e + able = desirable
* Add ‘–ible’ when the root is not a complete word. For example:
Horr + ible = horrible
Permiss + ible = permissible
Aud + ible = audible
* Add ‘–able’ when the word is new or modern. For example:
Email + able = emailable
Surf + able = surfable
Network + able = networkable
* As always is the case with the English language, there are exceptions. That is, none of the above apply. For example:
‘Contempt’ is a complete word, but ‘–ible’ is added, not ‘–able’ … contemptible
‘Response’ ends in ‘e’, but ‘–ible’ is added after dropping the ‘e’, not ‘–able’ … responsible
So, what should you do when you’re confused as to which suffix to use? Do one of the following:
1. Learn the spellings.
2. Look the word up in the dictionary.
3. Remember the hints above.
4. If there’s no dictionary around and you can’t remember either the spellings or the hints, just add ‘–able’. There is 5:1 chance you’ll get it right, because according to a research, there are only about 150 words that end in ‘–ible’. All the rest end in ‘–able’.
What do you do to remember which suffix to use?