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]