In
this series of lessons, you will learn useful spelling rules
in
English.
This lesson will provide guidelines on adding the suffixes -able
and -ible.
They have the same meaning, so it is important to know when you should
use each one.
As we have seen in a previous lesson, a suffix is an ending that can be
added to a word. The suffixes -able
and -ible
both create adjectives,
and they mean "can be done."
Choosing -able
or -ible
depends on the word the suffix is being added to. The suffix -able
is more common. Here are some rules to help you know which to use.
-able
1. When the base word before the suffix is a complete word
Years ago, it was fashionable
for ladies to wear gloves at formal events.
In the sentence above, "fashionable" means stylish. The part of the
word before the suffix -able
is a complete, recognizable word: fashion.
In cases like this, you will use -able
and not -ible.
Notice that words that end in -ce
and -ge keep
their final -e
before adding -able.
There are also a few important exceptions that keep their final -e,
which you should memorize: sizeable, likeable, nameable.
Here are some examples:
noticeable
changeable
manageable
laughable
transferable
preferable
suitable
impressionable
adaptable
likeable
peaceable
knowledgeable
comfortable
washable
affordable
sizeable
likeable
nameable
2. When the base word ends in an -e that is eliminated
Lily did not like the movie because it was not very believable.
Often, base words that end in -e
need to have that final -e
eliminated before adding -able.
When this happens, you should use -able
and not -ible.
As we saw above, base words that end in -ce and -ge keep their final -e before adding -able.
Here are some common examples:
debatable
pleasurable
adorable
desirable
measurable
conceivable
excusable
excitable
disposable
3. When the last consonant of the base word must be doubled
or the final -y must be changed to an -i
Kelly's surprise party was really unforgettable
for her.
When the base word ends ing a single vowel and a single consonant, and
the emphasis is on the last syllable
of the word, that final consonant
must be doubled before adding the suffix -able.
For more on this, you can check our lessons on adding -ing or adding -ed.
Also, when the base word ends in a consonant and a -y, that -y must be
changed to an i before adding -able.
In these cases, you should use -able
and not -ible.
For example:
forgettable
justifiable
reliable
regrettable
-ible
Dancing is a great way to stay flexible
and healthy.
Finally, in general when the base word is not a complete and
recognizable word, you should use -ible.
However, this is not a strict rule. It is important to be careful using
-ible.
You will see that many base words end in -t before the -ible
is added. You can look for this pattern. Also, you will never see a
final -e
before -ible.
Here are some common words with -ible:
terrible
horrible
visible
responsible
invincible
accessible
sensible
incredible
illegible
eligible
convertible
suggestible
digestible
Review
So, let's review what we have learned about the suffixes -able
and -ible
in English:
When the base word is a complete and recognizable word, you
will usually use -able.
When the base word ends in -e, you should remove
then -e,
then add -able.
Leave the -e
when the word ends in -ce
or -ge.
If you must double the final consonant of the base word or
change the final -y
to i, add -able.
In general, -ible
is less common and the base word is not a complete and recognizable
word. However, there are some exceptions.