Fatigue Meaning: Here’s What It Means and How to Use It

Not sure what fatigue means? Read on to discover everything you need to know about the meaning of fatigue, including definition, synonyms, and more.

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If you’re feeling especially sleepy after pulling an all-nighter, is that fatigue? Not necessarily — this article is here to help you understand the meaning behind fatigue, its symptoms, and more.   

What Does Fatigue Mean?

fa·tigue [ fuh-teeg ]

According to the National Cancer Institute, fatigue can be defined as a condition marked by extreme tiredness, weakness, and an inability to function due to lack of energy. 

To further your understanding of the term, let’s also review the definitions provided by a few additional reputable sources listed below:

  • The Collins Dictionary defines fatigue as a feeling of extreme physical or mental tiredness. 
  • Dictionary.com says fatigue is a noun that refers to weariness from bodily or mental exertion. 
  • According to the journal Biological Research for Nursing, fatigue can be defined as an “overwhelming, debilitating, and sustained” exhaustion that makes it very challenging to carry out activities and function.  

After reviewing these definitions, we can conclude that fatigue means extreme tiredness resulting from mental or physical exertion or illness. In other words, it’s a state of having no energy or motivation.  

What Is Fatigue?

The term fatigue may have originated from French Latin fatigare, meaning “to make tired” or “to exhaust,” but it means much more than just being sleepy. Fatigue can make it difficult to get out of bed in the morning and even prevent someone from fulfilling their daily tasks.

Not to get confused with drowsiness (which refers to the need for sleep) or apathy (which refers to a feeling of not caring about what happens), fatigue is a feeling of constant exhaustion. It can be physical, mental, or a combination of both. 

What’s more, fatigue can cause a wide range of other symptoms, including:

  • Chronic tiredness
  • Dizziness 
  • Headache
  • Sore or aching muscles
  • Impaired decision-making and judgment
  • Slowed reflexes and responses
  • Appetite loss
  • Impaired hand-to-eye coordination
  • Moodiness
  • Blurry vision
  • Poor memory
  • Poor concentration and focus
  • Hallucinations
  • Low motivation

What Causes Fatigue?

There are a number of causes that can trigger fatigue, including:

  • Physical health conditions, such as anemia, arthritis, fibromyalgia, and diabetes
  • Mental health issues, such as anxiety, depression, and seasonal affective disorder
  • Lifestyle factors, such as lack of sleep, being overweight, boredom, grief, etc.

If you’re feeling fatigued after making positive changes to your lifestyle, such as getting the recommended 7 to 9 hours of shut-eye each night, it’s a good idea to make an appointment with your doctor. In some cases, your fatigue might be caused by a serious medical condition. 

Tips to Reduce Fatigue

To help combat fatigue and boost your energy levels, check out these great tips provided by Gundersen Health System listed below:

  • Prioritize bedtime
  • Stay hydrated
  • Exercise
  • Reduce alcohol intake
  • Watch your meal portions
  • Keep stress levels in check
  • Aim to eat nourishing whole foods
  • Avoid caffeine late in the day

What Are Synonyms and Antonyms of Fatigue?

To further your understanding of fatigue, it can be helpful to learn its synonyms and antonyms. In short, synonyms are terms that have the same or almost the same meaning as another word. Antonyms are terms that have the opposite meaning of another word. 

The synonyms of fatigue include:

  • Tiredness
  • Weariness
  • Exhaustion
  • Overtiredness
  • Drowsiness
  • Somnolence
  • Lethargy
  • Sluggishness
  • Lack of vitality
  • Ennui
  • Listlessness
  • Grogginess

Antonyms of fatigue include:

  • Energy
  • Vigour 
  • Energetic
  • Untired
  • Fresh
  • Lively
  • Invigorated
  • Alert
  • Refreshed
  • Vivacious

The Word Fatigue in Example Sentences 

Now that you understand what fatigue means, let’s take a look at a few examples of the term used in a sentence, shall we?

Did you know that when fatigue is chronic, it can be its own condition, known as chronic fatigue syndrome?

Your new medications could be the culprit behind your recent fatigue.

Lifestyle factors such as poor sleep and an unhealthy diet could most definitely cause fatigue.

To diagnose you with fatigue, your doctor will check your medical history and perform a physical examination to check for signs of illness.

Before I started yoga, I was super fatigued.

Sometimes, fatigue is one of the many signs of illness.

The Centers for Disease Control and Prevention (CDC) says worker fatigue can have a devastating public safety impact, particularly in occupations with high-risk consequences!

Fatigue is a common symptom of heart disease.

Good nutrition is key to combating fatigue.

If you were recently in labor, had surgery, or suffered a bereavement, there’s a good chance that you might be feeling fatigued.

Before prescribing you a medication to treat your fatigue, a doctor will check for an underlying medical condition as it could be the culprit behind your exhaustion.

If you have unexplained fatigue as well as a fever, you may have caught the coronavirus!


Simply put, fatigue means a feeling of constant tiredness that can be caused by a number of health conditions and lifestyle factors, such as diabetes, chronic pain, and depression. Accompanied by a lack of motivation and the constant desire to take a nap, fatigue can make it extremely challenging to fulfill your daily tasks. 

If you feel as though fatigue has been plaguing your life for more than two weeks, you should make an appointment with your doctor for advice. 


  1. Fight off fatigue with these tips and tricks | Gundersen Health System
  2. A Systematic Review of Biological Mechanisms of Fatigue in Chronic Illness | Lea Ann Matura, Susan Malone, Rosario Jaime-Lara, Barbara Riegel, 2018 | Sage Pub
  3. Fatigue Definition & Meaning | Dictionary.com
  4. Fatigue definition and meaning | Collins English Dictionary
  5. Definition of fatigue | NCI Dictionary of Cancer Terms