Of a task, or the like: Which brings no thanks; receiving or deserving no thanks.

Of or relating to Sisyphus; resembling Sisyphus or that of Sisyphus; (of labour, a task, etc.) endless, laborious, and ineffective; = Sisyphean, adj.

used attributively.

Of or relating to Sisyphus, in Greek mythology a king of Corinth who was condemned in Hades endlessly to roll a heavy stone up a hill only for it…