Words ending in -able and -ible

Do you know whether a word ends in -able or -ible?

This can be difficult because both endings usually sound the same. However, there are some useful patterns that can help you with spelling and word formation.

1. When do we use -able?

A useful pattern is that -able is often added to a recognisable English word.

For example:

comfort → comfortable
enjoy → enjoyable
predict → predictable
prevent → preventable
reason → reasonable
sustain → sustainable

So, when you see a word ending in -able, ask yourself:

👉 Can I recognise the word before -able?

If you can, -able is often the correct spelling.

But remember, this is a pattern, not a rule that works for every word.

2. What about -ible?

Many common -ible words don’t have an obvious English root that you can simply add -ible to.

For example:

• horrible
• possible
• terrible
• visible
• audible
• credible
• edible
• responsible

You can’t use a simple rule to predict the spelling of all of these, so it’s important to learn them as vocabulary.

A useful tip

There are many more words ending in -able than -ible.

So if you’re trying to remember a word and you’re genuinely unsure, -able is more common.

⚠️ Don’t treat this as a spelling rule, though. Some very common words use -ible, such as possible, visible and responsible.

3. There are exceptions

English wouldn’t be English without exceptions!

For example:

access → accessible

You can clearly recognise the word access, but we don’t write accessable.

Other examples include:

• flex → flexible
• resist → irresistible
• convert → convertible

And some -able words don’t have an obvious root either:

• available
• inevitable
• probable
• vulnerable

So don’t waste time trying to find one perfect rule. Learn the patterns, then learn the common exceptions.

Quick practice

Choose -able or -ible.

1. predict___

2. poss___

3. comfort___

4. flex___

5. accept___

6. respons___