Used when someone is not focusing on what they should be, often unintentionally.

Lack of focus

Can indicate daydreaming or getting lost in thoughts unrelated to the present.

Mind wandering

Zoning out isn't always bad. Sometimes it's a natural response to a monotonous activity.

Indicates a disconnection due to a substance's effect on the brain.

Highlights a temporary loss of awareness that eventually passes.

It may be presumed that zoning out was intentional, which is not always true.