What is "sofa bedstead"

Sofa \So"fa\, n.; pl. Sofas. [Ar. soffah, from saffa to dispose in order: cf. F. sofa, It. sof[`a].] A long seat, usually with a cushioned bottom, back, and ends; -- much used as a comfortable piece of furniture.

Let fall the curtains, wheel the sofa round.
--Cowper.

Sofa bed, a sofa so contrived that it may be extended to form a bed; -- called also sofa bedstead.