1. A chronic inflammatory disease that causes progressive weakness and degeneration of skeletal muscles, typically affecting the shoulders, hips, and thighs.
Usage: medical term; uncountable noun; often abbreviated as PM

Examples

• Polymyositis is an autoimmune disorder that requires long-term medical management.
• Patients with polymyositis often experience difficulty climbing stairs or lifting objects.
• The doctor diagnosed her with polymyositis after blood tests showed elevated muscle enzymes.
• Physical therapy is an important part of treatment for polymyositis.
• Polymyositis can sometimes occur alongside other connective tissue diseases.