-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. See ability.

• (Received Pronunciation) IPA^(key): /-əˈbɪl.ɪ.ti/
• (UK) IPA^(key): /-əˈbɪl.ə.ti/
• (US, Canada, General Australian) IPA^(key): /-əˈbɪl.ə.ti/, [-əˈbɪl.ə.ɾi]

-ability (noun-forming suffix, usually uncountable, plural -abilities)

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

   ‎cook + ‎-ability → ‎cookability

• 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).