edema

the word edema entered english in the late 14th century via medical latin, which borrowed it from the greek word "oidēma," meaning "a swelling." this greek term itself derives from the verb "oidein," which means "to swell." the ultimate origin is the proto-indo-european root h₂eydʰ-, also signifying "to swell" or "to burn," a root that connects the concepts of swelling and inflammation. the journey from the ancient, concrete action of swelling to the modern, specific medical term for fluid retention demonstrates the specialized preservation of classical vocabulary in scientific language.

the entire word "edema" is a simplex unit borrowed directly from greek. it does not contain separable, productive morphemes in modern english spelling.