-ible

-able

If the root is not a complete word, add -ible.

aud + ible = audible

Examples:

• visible

• horrible

• terrible

• possible

• edible

• eligible

• incredible

• permissible

If the root is a complete word, add -able.

accept + able = acceptable

Examples:

• fashionable

• laughable

• suitable

• dependable

• comfortable

If the root is a complete word ending in -e, drop the final -e and add -able.

excuse - e+ able = excusable

Examples:

• advisable

• desirable

• valuable

• debatable