Spelling words ending in ‘-able’ and ‘ible’

Some adjectives end in the letters ‘-able’ or ‘ible’. They mostly refer to the ability or necessity to do something e.g. ‘washable’ (you can wash it), ‘visible (you can see it), ‘emailable’ (you can email it), and the pronunciation is the same. So how on earth do you know which spelling to use?

There are several approaches we can take depending on the person who is trying to learn it.
If I have a student who really struggles with spelling of even very common and simple words, then whether to use ‘-able’ or ‘-ible’ isn’t their greatest priority and I would use Hint 1:


Hint 1: It is much more common for words to end in ‘able’ than ‘ible’. So if you don’t know and there’s no dictionary around, use ‘able’ – you’ve got about a 5:1 chance of being right!

But obviously that’s not good enough for some people. If I was teaching someone who had a reasonable knowledge of the English language I’d get them to look at some ‘-able’ and ‘-ible’ words and notice the following:

Hint 2: Generally we use ‘-able’ when a complete word remains (or just without a final silent ‘e’, or a ‘y’ changed to ‘i’) when we take the suffix away. So for example, ‘fashionable’ – ‘fashion’ is a complete word, so add ‘-able’. But ‘edible’ – ‘ed’ is not a complete word meaning ‘eat’ so it’s ‘-ible’. Of course (being English!) this isn’t always true but it’s a good guide. If that doesn’t help, try this:

Hint 3: Play around with the root word and see if you can make any words with ‘-ation’ with it. So if you don’t know if it’s ‘applicable’ or ‘applicible’, think of ‘application’. If you can make an ‘-ation’ word then it’s probably ‘-able’. So here it’s ‘applicable’. But if you play around with it and can only make an ‘-ition’ ‘-tion’, ‘-sion’, ‘cian’ or ‘-ion’ word it’s much more likely to be ‘-ible’. For example, it’s ‘visible’ because of ‘vision’.

This should satisfy most learners but let’s say I am teaching someone who has studied Latin or is a bit of a linguist. They are not usually the ones who come to me with spelling problems but if they do:

Hint 4: If the root comes from a Latin verb ending in ‘are’, use ‘able’. If it comes from an ‘ire’ or ‘ere’ word use ‘ible’.

Hint 5 is for anyone:

Hint 5: New words are often made with ‘-able’, but not ‘-ible’: ‘emailable’, biodegradable’, ‘clickable’, ‘offsetable’, ‘recession-proofable’. (I may have made the last two up but they are allowable!)