Opacity (noun)

1. The quality or state of being opaque, or not transparent.
2. The degree to which a material allows light to pass through it, with a lower opacity meaning that more light can pass through.
3. The degree to which an image or object obstructs the view of what is behind it.

Origin:

The word 'opacity' comes from the latin word 'opacitas', which means 'darkness' or 'obscurity'. it has been used in english since the 16th century to describe the quality or state of being opaque.

Examples:

1. The opacity of the curtains allowed only a limited amount of light to enter the room.
2. The opacity of the glass made it difficult to see what was inside the bottle.
3. The opacity of the oil spill made it difficult to see the fish and other sea life below the surface.
4. The opacity of the clouds prevented the sun from shining through and the sky was overcast.
5. The opacity of the computer screen was adjusted to reduce glare and make it easier to see the display.