When fluid accumulates in a limited area, it is "localized edema". Edema distributed throughout the body as depicted in these puppies is referred to as "generalized edema".
The prefix "hydro" is often added to the anatomic site to denote edema in a particular area. Examples include hydroperitoneum (ascites), hydrothorax, hydrosalpinx, hydropericardium, and hydrocephalus. The word "hydrops" is sometimes used in a manner similar to the prefix "hydro", e.g. "hydrops of the gall bladder" or "hydrops amnion". Have you ever heard of the term "dropsy"? It is an old-fashioned word for chronic heart failure and got its origins from the generalized edema that heart failure can cause.