What is the antonym for effect?

The antonym for "effect" depends on the context. Here are some possibilities:

If "effect" means "result":

* Cause

* Origin

* Source

* Reason

If "effect" means "impact":

* Ineffectiveness

* Lack of impact

* No consequence

* Neutralization

If "effect" means "impression":

* Indifference

* Apathy

* Unimportance

* Lack of interest

If "effect" means "appearance":

* Reality

* Substance

* Truth

* Authenticity

Please provide more context if you need a more precise antonym.