Final answer:
Muscle weakness is referred to as atrophy, a condition characterized by a decrease in muscle mass due to various diseases and disorders like cancer, AIDS, Duchenne muscular dystrophy, and myasthenia gravis.
Step-by-step explanation:
The word that means muscle weakness is atrophy. Muscle atrophy is a decrease in muscle mass, which can be caused by a variety of diseases and conditions such as cancer, AIDS, congestive heart failure, and liver diseases, contributing to a body wasting syndrome known as cachexia.
Conditions like Duchenne muscular dystrophy (DMD), a genetic disorder, lead to the progressive weakening of skeletal muscles due to a lack of dystrophin protein. This deficiency results in damage to muscle cells during contractions, ultimately causing loss of muscle mass and strength. Moreover, myasthenia gravis is a genetic neuromuscular disorder where the immune system blocks acetylcholine receptors on muscle cells, causing progressive muscle weakness and fatigue.