Spelling Rules -- Is It "-Ible" or "-able?"


-ible -able
If the root is not a complete word, add "-ible."
For example, aud + ible = audible
If the root is a complete word, add "-able."
For example, accept + able = acceptable
Examples:
  1. visible
  2. horrible
  3. terrible
  4. possible
  5. edible
  1. eligible
  2. incredible
  3. permissible
  4. admissible
  5. compatible
  1. treatable
  2. actionable
  3. suitable
  4. dependable
  5. comfortable
  1. reachable
  2. lamentable
  3. reasonable
  4. repeatable
  5. mentionable
If the root is a complete word ending in -e, drop the final -e and add -able.
excuse - e+ able = excusable
Some exceptions to the rules:
  1. advisable
  2. desirable
  3. valuable
  4. debatable
  1. adorable
  2. accusable
  3. admirable
  4. achievable
  1. contemptible
  2. digestible
  3. flexible
  4. responsible
  1. irritable
  2. inevitable
  3. formidable
  4. accessible