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In Part 1 of this post, we established that, purely from a statistical perspective, if confronted with a word that may end in –able or –ible, you’d be much better off guessing –able. But spellers are not necessarily statisticians. So let’s go to a more linguistic argument.

Similar suffixes and –ible

One reliable way to determine which suffix to spell involves looking at other suffixes. Let’s say, for the sake of argument, that you’re looking at the word that begins with the letters corrod—. Would it end in an -ible or -able? Well, the base of this word is the word corrode, meaning “to slowly break apart or destroy through a chemical process.” (For example, acid can effectively corrode an iron pipe.) As it turns out, there is another form of this word: the word corrosion. And this word ends in the suffix –ion. The suffix begins with the letter “i”. This indicates that the suffix –ible may be the correct one. And it is! The correct spelling is corrodible.

Here are a few more examples of words ending in –ible that follow this rule:

  • omit / omission / omissible
  • divide / divisive / divisible
  • comprehend / comprehension / comprehensible
  • respond / responsive / responsible

Similar suffixes and –able

This same argument can apply to words that end in -able. For example, take the word remunerate. It turns out that the suffix –ate, beginning with the letter “a,” already indicates ending the word with –able. But you can even change the suffix into another one beginning with the letter “a,” and create the word remuneration. By now, it should be obvious that the suffix to use here is –able, and the correct spelling is remunerable.

Here are a few more examples of words ending in –able that follow this rule:

  • lacerate / laceration / lacerable
  • inhabit / inhabitate / inhabitable
  • assimilate / assimilation / assimilable


As always, this rule isn’t foolproof. As sure as death and taxes come the exceptions to spelling rules. Here are a few to be aware of:

  • resist / resistance / resistible
  • evade / evasion / evadable
  • conceive / conception / conceivable

And yet, even these last two words (evadable and conceivable) follow a logical pattern! What is it? We’ll find out on our next post on this byzantine spelling question.

Photo credit: “Question mark in Esbjerg” by alexanderdrachmann is licensed under CC BY-SA 2.0