different between listlessness vs tedium

English

From listless +? -ness.

listlessness (countable and uncountable, plural listlessnesses)

The state of being listless; apathetic indifference; lethargy.
- 1749, John Cleland, Fanny Hill: Memoirs of a Woman of Pleasure, Letter the First,^[1]
  But every thing must have an end. A motion made by this angelic youth, in the listlessness of going off sleep, replac'd his shirt and the bed-cloaths in a posture that shut up that treasure from longer view.
- 1851, Herman Melville, Moby-Dick, Chapter 35,^[2]
  […] lulled into such an opium-like listlessness of vacant, unconscious reverie is this absent-minded youth by the blending cadence of waves with thoughts, that at last he loses his identity; takes the mystic ocean at his feet for the visible image of that deep, blue, bottomless soul, pervading mankind and nature; and every strange, half-seen, gliding, beautiful thing that eludes him; every dimly-discovered, uprising fin of some undiscernible form, seems to him the embodiment of those elusive thoughts that only people the soul by continually flitting through it.

Latin taedium, from taed?re (“to weary”).

tedium (usually uncountable, plural tediums or tedia)

Boredom or tediousness; ennui.
- 1826, Mary Shelley, The Last Man, part 1, chapter 8
  Yet active life was the genuine soil for his virtues; and he sometimes suffered tedium from the monotonous succession of events in our retirement.
- 1975, Saul Bellow, Humboldt's Gift [Avon ed., 1976, p. 192]:
  Nothing actual ever suits pure expectation and such purity of expectation is a great source of tedium.

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