noun
trapdoor; removable floor board; lift-up lid
Refers to a hinged or removable cover set into a floor, ceiling, or countertop, often providing access to a space below. Common in traditional Japanese architecture and modern utility access panels.
See also: 上板
床下収納の上げ蓋を開けて、掃除機をしまった。
I opened the trapdoor to the underfloor storage and put away the vacuum cleaner.
カウンターの上げ蓋を外すと、配管が見える。
When you remove the counter's lift-up lid, you can see the plumbing.
Rarely used kanji form; 揚げ implies deep-frying, which is unrelated to the meaning.
上板 (あげいた) is a similar term for a removable board or panel, but 上げ蓋 specifically implies a lid that can be lifted, often hinged, while 上板 may simply be a board placed on top.
Compound of 上げ (age, 'lifting') + 蓋 (futa, 'lid'). The spelling 上蓋 uses 上 (ue, 'up') instead of 上げ, but the reading remains あげぶた.