Real Dictionary

futon
countable noun: A futon is a piece of furniture which consists of a thin mattress on a low wooden frame which can be used as a bed or folded up to make a chair.

futon in American English
a thin mattress like a quilt, placed as on the floor or a platform frame, for use as a bed
noun: a thin mattress, usually filled with layers of cotton batting and encased in cotton fabric, placed on a floor for sleeping, esp. in traditional Japanese interiors, and folded and stored during the day

futon in British English
noun: a Japanese padded quilt, laid on the floor for use as a bed, or on a frame for use as a chair