abri air-raid shelter airtight secrecy asylum bolt-hole bomb shelter bombproof bunker cache cave close secrecy closeness corner cover covert coverture cranny crypticness cubby cubbyhole cyclone cellar dark corner den disappearance discreetness discretion dugout earth evasion evasiveness fallout shelter foxhole funk hole hiddenness hideaway hideout hidey hole hiding hiding place hole hugger-mugger hugger-muggery immateriality imperceptibility indiscernibility invisibility lair niche nonappearance nook recess refuge retreat safety zone sanctuary secrecy secret place secretiveness secretness shelter stash storm cave storm cellar subterfuge the dark the invisible the unseen trench uncommunicativeness undercovert unperceivability unseeableness unsubstantiality viewlessness