What is the definition or description of: fluid in the lungs?

Fluid around lungs: Fluid around lungs has many causes. It can be exudate(thick i.E pus from infection, malignancy etc) or transudative(heart failure). It may be treated based on the problem found by sampling(thoracentesis). Labs on the fluid help the clinician determine the etiology. For recurring pleural fluid, sometime pleuradesis is necessary to hep prevent recurrance. Need diagnosis for proper resolution.