noun
myasthenia
Medical term for muscle weakness; often used in compound names like 重症筋無力症 (myasthenia gravis).
筋無力症は、筋肉の脱力や疲れやすさを引き起こす病気です。
Myasthenia is a condition that causes muscle weakness and easy fatigability.
Myasthenia gravis, a specific autoimmune form of myasthenia; 筋無力症 is the broader term for muscle weakness.
Compound of 筋 (muscle), 無力 (powerlessness), and 症 (condition/disease).