-ability

• -ibility

From Middle English -ablete, -iblete, -abilite, -ibilite, from Middle French -ableté, -ibleté, -abilité, -ibilité, from Latin -abilitas, -ibilitas, from -abilis (“able”) or -ibilis (“able”) + -tas. Equivalent to -able + -ity.

• (US) IPA^(key): /əˈbɪl.ə.ti/

-ability

1. Forms a noun from a verb or an adjective by changing from -able; ability, inclination or suitability for a specified function or condition.

   vulner(able) → vulnerability

• This suffix is equivalent to -able + -ity, but as it involves both a sound and spelling change it can be seen as a suffix in its own right. Compare -ification (equivalent to -ify + -ation).