disease - an impairment of health or a condition of abnormal functioning

myasthenia, myasthenia gravis - a chronic progressive disease characterized by chronic fatigue and muscular weakness (especially in the face and neck); caused by a deficiency of acetylcholine at the neuromuscular junctions

carcinomatous myopathy, Eaton-Lambert syndrome, Lambert-Eaton syndrome, myasthenic syndrome - a disease seen in patients with lung cancer and characterized by weakness and fatigue of hip and thigh muscles and an aching back; caused by antibodies directed against the neuromuscular junctions