Denoting a task that can never be completed.
Late 16th century: from Latin Sisypheius (based on Greek Sisuphos: see Sisyphus)+ -an.
“It was a sisyphean task but she stuck at it.”
An antechamber, hall, or lobby next to the outer door of a building.
Early 17th century (denoting the space in front of the main entrance of a classical Roman or Greek building): from French, or from Latin vestibulum ‘entrance court’.