What does density in a chest xray mean?

Nonspecific: Density usually refers to something replacing what is normally air filled lung. Pneumonia, scarring, tumors, fluid, and lung that is not filling normally with air can do this.

Usually opacity: Density or consolidation on chest x-ray is increased density replacing normally clear ventilated lung.. Density is usually nonspecific and can represent pneumonia, hemorrhage, collapsed lung, tumor, fluid, etc.There are different dnesities going from lucent lungs (least dense), to fat, soft tisue and bone (most dense) on chest x-ray