1. Accumulation of fluid in the lungs due to left-sided failure of the heart. 2. Swelling; accumulation of excessive fluid in subcutaneous tissues (beneath the skin.) 3. A condition characterized by an abnormal accumulation of fluid; usually caused by the heart’s inability to pump blood at sufficient pressure, a condition known as congestive heart failure. 4. The medical term for an abnormal accumulation of body fluid within the tissues. It may be visible, as in a swelling, or localized, for example at the site of any injury, or generalized, as in some heart conditions. The ankles are common sites of edema. 5. Local or generalized condition in which body tissues contain an excessive amount of tissue fluid. 6. An abnormal accumulation of liquid in tissue, such as in the legs or feet.