opacity

noun4

1. •
   The state or quality of being opaque, not allowing light to pass through.

   • We could not see the sandbar due to the opacity of the muddy water.
2. •
   A measure of relative impenetrability to electromagnetic radiation such as light.

   • The opacity of a clean glass window is near zero.
3. •
   An opaque area.

   • This report concerns a child with Down's syndrome (mongolism) and bilateral congenital corneal opacities born into a family affected through three generations by Rieger's anomaly. — 1968
4. •
   The state or quality of being inaccessible to understanding.

   • The opacity of these decisions is troubling.