lassitude has definitions from the fields of psychology,medicine
1
[ noun ] (psychology) a feeling of lack of interest or energy

Related terms

apathy

2
[ noun ] (medicine) a state of comatose torpor (as found in sleeping sickness)

Related terms

torpor hebetude

3
[ noun ] weakness characterized by a lack of vitality or energy

Synonyms

lethargy inanition

Related terms

weakness

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