Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

See What's Trending Now See More Trending Words

chronic fatigue syndrome

noun

Definition of chronic fatigue syndrome

:a disorder of unknown cause that is characterized by persistent profound fatigue usually accompanied by other symptoms (such as headache and tender lymph nodes) unrelated to any preexisting medical condition —abbreviation CFS

See chronic fatigue syndrome defined for English-language learners

Indulge Your Inner Word Nerd

alt-59c94ad823f29
'Meat Sweats': The Cookout's Worst Nightmare
image1644821030
These Are Fighting Words
video-title-words-of-the-year-1066
Words of the Year: 1066
young-plant-shoots
Merriam-Webster's New Words Quiz—Fall 2017 Edition!

First Known Use of chronic fatigue syndrome

1947

CHRONIC FATIGUE SYNDROME Defined for English Language Learners

chronic fatigue syndrome

noun

Definition of chronic fatigue syndrome for English Language Learners

  • medical : an illness that makes you feel very tired for a very long time and that often includes other symptoms such as headaches and weakness

Medical Dictionary

chronic fatigue syndrome

noun

medical Definition of chronic fatigue syndrome

:a disorder of uncertain cause that is characterized by persistent profound fatigue usually accompanied by impairment in short-term memory or concentration, sore throat, tender lymph nodes, muscle or joint pain, and headache unrelated to any preexisting medical condition and that typically has an onset at about 30 years of age —abbreviation CFS — called also myalgic encephalomyelitis

Learn More about chronic fatigue syndrome

  1. Britannica.com: Encyclopedia article about chronic fatigue syndrome

Seen and Heard

What made you want to look up chronic fatigue syndrome? Please tell us where you read or heard it (including the quote, if possible).

show hide

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

broadside

play

a strongly worded attack

Get Word of the Day daily email!

TRENDING NOW

  1. dotage, dotard a state or period of senile decay

  2. otherwise "in other respects"

  3. federalism Graham says bill gives power to states

  4. bodega "Don’t mess with the beloved bodega."

  5. carceral Of, relating to, or suggesting a jail or prison

SEE ALL

BROWSE DICTIONARY

chronic fatigue syndrome

Test Your Vocabulary

Merriam-Webster's New Words Quiz—Fall 2017 Edition!

  • young-plant-shoots
  • Which of the following is a new sense of the word bunny?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

alt-59c94ad823f29
'Meat Sweats': The Cookout's Worst Nightmare

They're real, but is meat the cause?

alt-59c919f342079
'Diffuse' vs. 'Defuse'

Let us defuse the situation.

alt-59c52d6ee2f72
Breathing Life Into 'Inspire'

The word's origins are quite literal

alt-59c4207ecf106
Let's Talk 'Tea'

Spill it, sip it: just make it hot.

Ask the Editors

video-title-words-of-the-year-1066
Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

payday
How Often Is 'Biweekly'?

Don't get us started on 'bimonthly'

video-irregardless-grammar-peeve-blend-of-the-synonyms-irrespective-and-regardless
Irregardless

It is in fact a real word (but that doesn't mean you should use it).

video-moose-goose-weird-plurals
Weird Plurals

One goose, two geese. One moose, two... moose. What's up with that?

Word Games

young-plant-shoots
Merriam-Webster's New Words Quiz—Fall 2017 Edition!

You're going to have to memorize the dictionary again.

Take the quiz
stylized-drawing-of-woman-pole-vaulting-across-gap-to-get-trophy
Challenging Vocabulary Quiz Returns!

No tricks, just difficult words.

Take the quiz
Name That Thing
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Take the quiz
Bee Cubed
Bee Cubed

Listen to the words and spell through all three levels.

Play the game