Edema, also spelled oedema, also known as fluid retention, dropsy, hydropsy, and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin that feels tight, the area may feel heavy, and joint stiffness. Other symptoms depend on the underlying cause. Causes may include venous insufficiency, heart failure, kidney problems, low protein levels, liver problems, deep vein thrombosis, infections, angioedema, certain medications, and lymphedema.

Source: Wikipedia