What is the collective noun of ignorance?

There isn't a widely accepted collective noun for ignorance.

However, we can be creative and come up with some options, depending on the context:

General Ignorance:

* A cloud of ignorance

* A veil of ignorance

* A sea of ignorance

* A swamp of ignorance

* A haze of ignorance

Ignorance of a Specific Topic:

* A void of knowledge (on a specific topic)

* A dearth of understanding (about a specific concept)

* A blank slate (of knowledge about a particular subject)

Ultimately, the best collective noun will depend on the specific situation and the desired effect.