The word you're looking for is opaque.
You cannot see through the material.
If it lets NO light through it can not even give a blurry view, so your question makes no sense and cannot be answered.
Opaque
yes
anything opaque
Light cannot pass through an opaque material.
You cannot see through the material.
If it lets NO light through it can not even give a blurry view, so your question makes no sense and cannot be answered.
Opaque
yes
a fanny
translucent
Water cannot pass through tyvek. Water vapor can however but liquid water cannot. Tyvek is high-density polyethylene fiber and is a synthetic material.
Insulators
anything opaque
That material would be included in the category of electrical "insulators".
An insulator.