布団

Etymology
Borrowed from written, possibly early Mandarin , likely as part of the importation of Zen Buddhism, for which practice these were originally used. First cited in Japanese to a text from the early-mid 1200s with the "meditation cushion" sense.

Originally referred literally to a, from the way these were round cushions made from woven bulrush leaves.

After the term was borrowed, the usage and construction of these cushions changed and the connection with bulrushes was weakened, leading to the simpler character being used as a replacement for.

Noun

 * 1)   a round cushion made of woven bulrush leaves, used for zazen seated Zen meditation
 * 2)   (zabuton, “seat / sitting cushion”)
 * 3)   traditional Japanese-style bedding, more specifically the  or, or a set of both, spread directly on a tatami floor

Usage notes

 * 布団 may refer to just the mattress, just the comforter, or the entire bed consisting of both.
 * Note that the Japanese term has no "furniture" sense, unlike the borrowed English term, which can refer to a specific kind of sofa-bed.