Oedema

Accumulation of excess fluid in tissue is called edema

Explanation: pleural fluid accumulates as a result of either increased hydrostatic pressure or decreased osmotic pressure (‘transudative’ effusion, as seen in cardiac, liver or renal failure), or from increased microvascular pressure due to disease of the pleura or injury in the adjacent lung(exudative)

Explanation -
Localized edema is generally due to cellulitis, chronic venous insufficiency, deep vein thrombosis, lymphedema, or May-Thurner syndrome. 

Explanation -
Causes of transudative oedema :
Protein energy malnutrition 
Liver cirrhosis
Malnutrition 
Protein losing gastroenteropathy

Causes of exudative ascities :
Heart failure
Cirrhosis
Portal vein thrombosis
Tuberculosis
Peritoneal tumor.