opaque

Impenetrable by light; neither transparent nor translucent.

Not reflecting light; having no luster.

Impenetrable by a form of radiant energy other than visible light.

So obscure as to be unintelligible.

Mentally obtuse; dense.

Something that is opaque, especially an opaque pigment used to darken parts of a photographic print or negative.

To render opaque.

Something opaque; specifically, a shade which can be worn over the forehead to protect the eyes from brilliant light.