lethargic

Etymology

From Ancient Greek ληθαργικός (lēthargikós), from λήθαργος (lḗthargos, “forgetful, lethargic”), from λήθη (lḗthē, “a forgetting, forgetfulness”) (from which Lethe (“river in Hades”)) + ἀργός (argós, “not working”).

adj

1. sluggish, slow
   [That cat] hasn't caught a mouse since he was a slip of a kitten. Except when eating, he does nothing but sleep. Lethargic is the word that springs to the lips. If you cast an eye on him, you will see that he's asleep now. 1960, P. G. Wodehouse, Jeeves in the Offing, chapter VII
2. indifferent, apathetic