English word incompetence comes from French -ence (-ence, -ance.), French incompétent (Incompetent.)

Detailed word origin of incompetence

Dictionary entry	Language	Definition
-ence	French (fra)	-ence, -ance.
incompétent	French (fra)	Incompetent.
incompétence	French (fra)	Incompetence.
incompetence	English (eng)	Inability to perform; lack of competence; ineptitude.

Words with the same origin as incompetence