I.up [美 əp, 英 ʌp]副up often appears as the second element of certain verb structures in English (back up, pick up, sit up, etc). For translations, see the relevant verb entry (back, pick, sit, etc).
It's a place full of claw-like arcades, moving floors that swallow up unwary adventurers, and that mainstay of action fantasy, walls that sprout spikes.