Definitions

chronic fatigue syndrome

NOUN

disorder involving extreme fatigue and weakness

Synonyms

WEAK

chronic fatigue and immune dysfunction syndrome fatigue disease fatigue syndrome myalgic encephalomyelitis post-viral fatigue syndrome postviral syndrome yuppie flu

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Healthy individuals had more of these bacteria than people with conditions such as inflammatory bowel disease, obesity, and chronic fatigue syndrome.

From Science Daily • Feb. 14, 2026

Katie Livings has chronic fatigue syndrome which causes exhaustion, headaches and sensitivity to light.

From BBC • Nov. 5, 2025

Among the most common co-occurring illnesses were chronic fatigue syndrome and mast cell activation syndrome, or MCAS, a condition where patients experience intense episodes of diarrhea, hives, vomiting, and, in many cases, life-threatening anaphylaxis attacks.

From Slate • Sep. 15, 2025

It is similar to chronic fatigue syndrome and can range from mild to debilitating.

From Los Angeles Times • Dec. 18, 2024

By giving the condition a name like "lymphoma" or "melanoma", "chronic fatigue syndrome" "Epstein-Barr syndrome" or "AIDS," "systemic yeast infection", "hepatitis" or what have, people think the doctor then understands their disease.

From How and When to Be Your Own Doctor by Solomon, Steve