Amnesia is the Greek word Αμνησία. It is composed by Greek word μνήμη (mnimi means memory) and a- which means the lack of something. So the memory loss is Amnesia.
Amnesia
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Discover ‘necrosis’, from Greek ‘nekros’ (dead body), a medical term for the uncontrolled death of cells in living tissue.
Anatomy Explained: Tracing the Definition and Greek Etymology of the Science of Body Structure
Etiology is the study of causation or origination. In medicine, it refers specifically to the cause or origin of a disease or disorder.