A state of sluggishness, inactivity, and lack of energy; abnormal drowsiness or indifference to one's surroundings. Can be physical, mental, or emotional.
From Greek 'lethargia' meaning 'forgetfulness, drowsiness,' from 'lethe' (forgetfulness) and 'argos' (idle). The word entered English through Latin in the 14th century, originally as a medical term for pathological sleepiness.
Lethargy is the noun form of lethargic - it's that heavy, can't-get-moving feeling. Think of the mythological river Lethe where souls forgot everything - lethargy makes you forget how to be active! It's like your energy just drained away into that forgetful river.
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