Edema, or water retention, occurs when fluid builds up in the tissues of the body. Learn about edema here. Oedema is a build-up of fluid in the ankles, feet or legs that can be caused by various factors. Learn how to recognise, treat and prevent oedema and when to see a GP. Discover the causes, symptoms, and treatment of oedema . Learn how fluid retention leads to swelling and ways to manage this condition effectively. Looking for online definition of oedema in the Medical Dictionary? oedema explanation free. What is oedema ? Meaning of oedema medical term. What does oedema mean?