noun
Medical term for amnesia or memory loss. Used in clinical contexts.
事故の後、彼は健忘症になった。
After the accident, he developed amnesia.
記憶喪失 is a more general term for memory loss, while 健忘症 specifically refers to the medical condition of amnesia.
From 健 (healthy) + 忘 (forget) + 症 (condition/syndrome), literally 'healthy-forget condition', a medical term for amnesia.