Clouding of the cornea, vision-impairing.

Clouding of the eye's lens.

A property of a linguistic construction where, for an expression built from it, replacing a subexpression with another one that denotes the same value may change the value of the expression.

Impediment to light transmission visibility.

Visibility of structures on radiographs.

a finding seen on chest x-ray (radiograph) or computed tomography imaging of the lungs.

When an electromagnetic wave travels through a medium in which it gets attenuated (this is called an "opaque" or "attenuating" medium), it undergoes exponential decay as described by the Beer–Lambert law.