They could only have come from the old man at my side, and yet he sat now as absorbed as ever, very thin, very wrinkled, bent with age, an opium pipe dangling down from between his knees, as though it had dropped in sheer lassitude from his fingers.
There are no more uses of "lassitude" in the book.
Show samples from other sources
They did not go hunting at all that night, but stayed near the den and rested, The next morning dawned fine and warm, and a general air of contented lassitude seemed to overcome all three.
Farley Mowat -- Never Cry Wolf
In every sense of the word having experienced rebirth, she possessed some of the lassitude and, as a matter of fact, a great deal of the helplessness of a newborn child.