Word Endings — -ible vs -able
I was talking with my friend Liz the other day and she mentioned that someone had asked on the Glen Mitchell show about whether there was any rhyme or reason behind why some words end in “able” (such as “comfortable”) while others end in “ible” (such as “horrible”). Before I get to the answer, though, here’s the scoop on the Glen Mitchell Show for readers who aren’t in Dallas — the show airs on Dallas’ local NPR affiliate and each Friday show features call-in questions which other audience members are invited to help answer. It’s a bit like Ask.MetaFilter but on the radio (HHOS).
Anyhow, you wouldn’t think that there’d be any reason behind such word endings, but there actually is (well, mostly).
If the root is not a complete word, add -ible. (aud + ible = audible)
If the root is a complete word, add -able. (accept + able = acceptable)
For example, “laugh” makes sense on its own, so that becomes “laughable”. On the other hand, “elig” can’t stand on its own, so that one’s “eligible”. Then again, English just isn’t allowed to be that easy ;), so there are some exceptions, such as “irritable” and “inevitable”.
:) This is one of the reasons I love the English language.
p.s. The Thesaurus is one of my favorite books. I’m such a geek.
how is “responsible” an exception to the rule?
is “respons” a complete word?
I’m not sure about that one, posy. Maybe “responsible” is based on “respond” or something?
the rule states:
If the root is a complete word ending in -e, drop the final -e and add -able.
i.e.
excuse – e+ able = excusable
therefore, reponse is an execption due to the fact that it uses ‘ible’ instead of ‘able’
i.e.
reponse – e + ible = reponsible
The drop the silent-e rule applies whether adding ible or able:
When adding a suffix that begins with a vowel to a root (Latin/Greek) or a root-word that ends with a silent-e, drop the e. Both ible and able begin with a vowel.
spons and spond are two spellings of the same Latin root.
accept is not a root-word:
prefix ac + Latin root cept = accept
There is a different generalization that helps for many, but not all, words like irritable.
If you can make a word ending in ation, able is usually the correct spelling:
irritation irritable
vegetation vegetable
If you can think of a word ending in ition or tion, ible is usually the correct spelling:
inflection inflexible (flex/flect same root)
audition audible
admission admissible
response is the root word. It isn’t an exception. There is another rule also states that you drop the final e before adding the suffix -ible or -able
so you get response – e + able = responsable
Posy, responsible is an exception to the superficial rule that states: “we should add +able to roots that are complete words. And here we are. Response is a complete word, our root in this case, and we drop the final silent -e as required. So why do we get -ible instead of -able? To figure this out let’s look deeper into the etymology of the word and notice that Latin words ending in -ERE, -IRE all get -IBLE suffixes in Modern english. At least in the examples I have researched myself. E.g. contemptIBLE (from contemnere), digestIBLE (from digerere), flexIBLE (from flectere), responsIBLE (from respondere) and watch out! irritABLE (irritARE), inevitABLE (evitARE). Does that answer your question?
What about “manageable?” Why is the “e” retained? Are there other examples of this anomoly?
So CONVERT is a complete word. Why then doesn’t CONVERTIBLE end with -able?
i don’t think it does. the only convetible is a car or to convert or change something
Elizabeth if response is the root word then it would be (responseable)
Perhaps the reasoning behind the particular “exceptions” has to do with the implications of the ible/able endings vs. the root word. For example, response has little to do with the word responsible.
In response to #9, the “e” is retained after the “g” in manageable, to keep the “j” sound of the g. Try saying “managable” – man-a-gable instead of man-a-jable.
what about accessible , access is a complete word.
access+able =accessable
None of this explains “deductible” nor “suggestible” which are the two words that led me to this discussion…