A Question About Adaptability

Annabel wrote:

I am a student of Maria Haeberli and we have come over a very funny word.

Adaptability. We have worked out there are two suffixes in it but we are not sure what the "i" after the "b" is doing there. The word sum that we have worked out is; adapt+ able + ity. Can you help us? Looking forward to your answer,

Annabel Fraser

A Question About :
<adaptability>

And my response:

Thank you for raising a very interesting question about the spelling of <adaptability>.

Your hypothesis is quite logical and makes sense, outside of that odd extra <i>. Your seemingly straight-forward question has made me think quite a bit about the reasons why and so, for me to determine whether or not your hypothesis is orthographically accurate, I needed to do some more investigation.

With any such analysis, I always collect as many examples as I can because that makes it easier for me to test the hypothesis (side panel 1). Your word <adaptability> is a great place to start and I can see you have already identified the stem <adapt>. I have thought up some other words that also use this type of suffix to help with my analysis (side panel 2).

I know that all these words are nouns just like <adaptability> so the final suffix must be noun-forming and in your hypothesis you have quite rightly identified the noun-forming suffix <-ity> .

I can deduce by removing this suffix (side panel 2) that the stems for all these words are adjectives and we write them in English using one of the 3 forms of the adjectival suffix <-able> (though <-ible> and <-uble> (very rare) are no longer 'living' suffixes and indicate words that have been in English for a long time),

So far your hypothesis holds up. In each of these cases the adjective form taking <-able> or <-ible> is transformed into a noun with the suffix <-ity>. And now I face your question: ‘Why is there a letter <i> between the letters <b> and <l>?’

At first glance I am led to postulate that it has to do with pronunciation. I know that every syllable in an English word must have at least one vowel letter in it, so I need to test this out with your starter words (side panel 3).

If I completed your word sum as you have written it (side panel 4), I am short a vowel letter and therefore this spelling is not possible in English. The <le> ending on the suffix <-able> is pronounced with a shewa before the / l / phoneme as we have in <little>, <saddle>, <puddle>. When the final <e> is removed and the 2^nd suffix added, we lose a letter to represent that shewa. But that still doesn’t explain why this letter is an <i>.

This is where good references are a huge benefit to Word Detectives like your classmates and you. I am lucky enough to have several such resources but if you have a good dictionary that can tell you about the origins of prefixes and suffixes as well as the words themselves then you are better able to research this type of question for yourself.

I had a strong suspicion that the <-abil-> spelling was of Latin origin and so looked up <-able> in my big Collin's dictionary to see what it had to say. I discovered that the suffix <-able / -ible> came into English via French from the Latin adjectival suffix <-ābilis / -ībilis> meaning 'worthy to be'. I have another useful little book "Oxford: Ologies and Isms" by Michael Quinion and I used this to confirm that this was indeed the case ( I never believe anything I read in a book unless I can back it up from another source).

So now I think I can add to your hypothesis the idea that in English there is a combined suffix with two forms: <-ability / -ibility> that came into being from the original Latin suffixes <-abil(is) + -ity>. This combined suffix is used to replace the adjectival suffix <-able / -ible> (which came into English via French) when you want to form the abstract noun from the base element meaning ‘the quality or condition of <-ity> being worthy or capable of <-able/-ible> … (whatever it is that is the base)’. When you do this you are able to ensure that there are sufficient vowel letters for the spoken syllables in the finished word.

I hope that I have answered your question clearly enough so that you can explain it to the rest of your class. You might like to collect even more words that use these suffixes and see if there are any situations where this pattern is not the case.