This question comes about because I usually always spell the word incorrectly and the spell checker underlines in red the word: compatible.
In my head, I always want to spell it compatable, and my logic is as follows.
First, look at a definition:
Definition of compatible a. - Capable of existing in harmony; congruous; suitable; not repugnant; -- usually followed by with.
There's a few words in there that make sense to my brain. Capable and suitable both have the -able suffix, because they can do something.
The root of the suffix is pretty self-explanatory. Able, suggestive of the ability to do whatever it is that the suffix is appended to.
Examples of words that make sense to me are:
- persuadable: the ability, or able-ness to be persuaded
- placable: [...] to be placed
- unappeasable: the inability, or unable-ness to be appeased
Other words of which the spellings are confusing to me: accessible, compatible, fallible, immersible
Why the -ible, and not -able when the end result seems to be expressing the same able-ness? To me, they should be spelled accessable, compatable, fallable, immersable.
What's the root of -ible being used and not -able?