Meaning

noun a state of comatose torpor (as found in sleeping sickness)

noun weakness characterized by a lack of vitality or energy

noun inactivity; showing an unusual lack of energy

originFrom Middle English litargie, from Medieval Latin litargia, from Late Latin lēthārgia, borrowed from Ancient Greek ληθᾱργῐ́ᾱ (lēthārgĭ́ā, “drowsiness”), from λήθᾱργος (lḗthārgos, “forgetful, lethargic”) + -ῐ́ᾱ (-ĭ́ā, adjectival suffix).

Etymology from Wiktionary, CC BY-SA 3.0