Definitions of incapable:

• adjective:   not meeting requirements
• adjective:   (followed by `of') lacking capacity or ability

  Example: "Incapable of carrying a tune"

• adjective:   (followed by `of') not having the temperament or inclination for

  Example: "Simply incapable of lying"

• adjective:   lacking the necessary skill or knowledge etc.

  Example: "An incapable helper"