牀
ショウ, ソウ, ゆか
bed, couch, bench, chassis
JLPT0 G13 S0 F5000
爿# long, wooden sleeping pallet + 木 tree/wood → (long and thin) wooden *bed* → wooden *stand*, *chair* or *couch*. Also, *wood floor*. Compare 床. Logically, the classifier for 牀 should be 木, but it is traditionally given as 爿.
[Full Kanji Etymology List]