noun
removable floorboard; trap door
Refers to a floorboard that can be lifted, often for access to a crawl space, storage, or a hidden area. Common in traditional Japanese architecture.
台所の上板を上げると、地下の収納スペースがある。
When you lift the removable floorboard in the kitchen, there is a storage space underneath.
古い旅館の廊下には、点検用の上
In the hallway of the old inn, there are several trap doors for inspection.
Compound of 上げ (age, 'lifting') + 板 (ita, 'board'). The kanji 上 is used as a simpler variant of 上げ.