1) Any muscular weakness 2) Muscle weakness 3) Myasthenia gravis 
Myasthenia is a medical term for muscle weakness. The term may also refer to: ==Medical conditions== ...
muscular weakness or debility
Muscular weakness.
(my- + Gr. astheneia weakness) muscular debility; any constitutional anomaly of muscle.
<anatomy, neurology> Muscular debility, any constitutional anomaly of muscle. ... Origin: Gr. Astheneia = weakness ... (18 Nov 1997) ... 
(mi″әs-the´ne-ә) muscular debility or weakness. adj., myasthen´ic., adj. myasthenia gravis an autoimmune disease of nerve and muscle function due to the presence of antibodies to acetylcholine receptors at the neuromuscular junction; characteristics include musc...
Weakness of muscles.
Type: Term Pronunciation: mī′as-thē′nē-ă Definitions: 1. Muscular weakness.
[n] - any muscular weakness
myasthenia Abnormal muscle fatigue or weakness.
muscle weakness.