lethargy

lethargy — noun

1. a heavy, tired feeling in which a person has very little energy and finds it dif

1.nounB2
Definition

a heavy, tired feeling in which a person has very little energy and finds it difficult to do even simple tasks or to care about things around them

Example

After lunch, Femi felt a wave of lethargy that made him want to nap instead of working.

a wave of lethargy — sudden onset collocation

The humid summer weather brought on a general lethargy in the whole household.

bring on + lethargy — cause collocation

Common collocations
  • wave of lethargy
  • bout of lethargy
  • deep lethargy
  • general lethargy
  • overcome lethargy
  • shake off lethargy
  • sink into lethargy
  • emerge from lethargy
Synonyms
  • fatigue

    emphasizes physical or mental exhaustion after effort; more specific cause-and-effect than lethargy

  • sluggishness

    focuses on slow movement and slow reaction; narrower than lethargy's broader inertia

  • listlessness

    highlights lack of interest or enthusiasm; overlaps with lethargy but leans more toward emotional flatness

  • torpor

    more extreme and literary; suggests a near-dormant state; less common in everyday speech

Antonyms
  • energy

    direct opposite — active drive and capacity

  • vigour

    suggests strength and healthy enthusiasm, not just the absence of lethargy

Usage Note

Unlike tiredness or fatigue, lethargy is not necessarily caused by physical exertion — it often feels involuntary and unrelated to how much rest or activity the person has had. Frequently appears with verbs like 'overcome,' 'shake off,' and 'sink into.'

Common Mistakes

I was fired for lethargy at work.
I was fired for laziness at work.
Lethargy is an involuntary state of low energy, not a deliberate choice to avoid work.
After a 10 km run, I felt lethargy in my legs.
After a 10 km run, I felt fatigue in my legs.
Lethargy describes a whole-body or mental lack of energy, not muscle-specific tiredness from exercise.

Word family

  • lethargic
    adjectiveB2
  • lethargically
    adverbC1

Synonym discussion

Sense: noun/1

The key difference between these words lies in cause and choice. Fatigue and tiredness generally result from physical or mental exertion — you feel tired because you have been working, studying, or exercising. Lethargy, by contrast, often has no obvious cause tied to effort; it can feel like a heavy blanket that makes even getting out of bed feel impossible. Laziness implies a voluntary choice: a lazy person could make an effort but decides not to. Sluggishness overlaps with lethargy but suggests slow physical movement rather than a complete lack of motivation or mental energy. For example: after a sleepless night, Paloma felt a deep lethargy that kept her in bed until noon. Calling that 'fatigue' would imply she had earned the tiredness through activity, which she had not.

fatigue ↗tiredness ↗lazinesssluggishness

Common collocations

Nouns

Adverbs

Phrases

  • overcome lethargy
  • shake off lethargy
  • sink into lethargy
  • emerge from lethargy
  • struggle with lethargy

Prepositions

Etymology

GreekLatinFrenchEnglish

The English word 'lethargy' comes from the Latin 'lethargia', which was borrowed from the Greek 'lēthargia'. The Greek root combines 'lēthē' (forgetfulness) and 'argos' (idle or lazy). In Greek mythology, Lethe was the river of forgetfulness in the underworld. So the word's original image was a state so heavy that a person forgot everything and became completely still — much like the modern sense of deep, unmotivated tiredness.