Word ending ible/able

[Hamburg]

A delightful young student in my class of advanced English, asked me this morning why some words ended in 'ible' and some with 'able', e.g. irresistible / understandable.
For the first time in many moons, I was stuck for an answer.
Who can help?
Many thanks in advance.

[BobK]

Well, I know why (historically). But I'd be interested to know if there's a useful rule of thumb for English learners.

The answer is in the suffixes: Latin -ibilis and English -able; so, as long you know the derivations, it's easy

b

[Hamburg]

Thanks for the prompt reply BobK.
If this is a case of Latin knowledge, then I'd better start right away with books I and II.
Oh well, Nihil sine labore or something like that.

[BobK]

Far be it from me to suggest anything so laborious. It'd be ridiculous to teach ELT students Latin just for the background. But a background knowledge of Latin helps in some cases (and hinders in others - I had to rethink my understanding of indirect objects just a few hours ago).

Incidentally, when I used the expression "the English suffix -able" I didn't mean it was English in itself, but rather that it was added on to English words as a productive mechanism in the development of English words: understand -able.

This is the way we get a few couplets in English -Vble words: "defendable" (defend -able) vs "defensible" (defens_ -ibilis) - they don't mean the same, but both words exist (although not everyone uses the second).

b

[Hamburg]

Originally Posted by BobK

I'd be interested to know if there's a useful rule of thumb for English learners.

OK folks, is there anyone out there with a 'rule of the thumb' for this situation?
Every little piece of information could help in a bigger way than you think.
Thanks again in advance.

[Hamburg]

Originally Posted by Hamburg

OK folks, is there anyone out there with a 'rule of the thumb' for this situation?
Every little piece of information could help in a bigger way than you think.
Thanks again in advance.

Don't tell me I've stumped the forum with this question!
Is there nobody out there with a simple way to discern between able and ible at the end of a word?
C'mon mates, get in there

[curmudgeon]

Here you go Hamburg, Easy peasy

Spelling: Suffixes -ible and -able

[Hamburg]

Curmudgeon, the drinks are on me, Mate.
Set them up barman

[curmudgeon]

Cheers

There are a few exceptions though so not entirely foolproof.

[Hamburg]

Originally Posted by curmudgeon

Cheers
There are a few exceptions though so not entirely foolproof.

Nae problem, ah'll findum.
Thanks again