(adv.) In a stealthy manner.

abri abstruse air-raid shelter armored asylum back-door backstairs beclouded between the lines blanket blind bolt-hole bomb shelter bombproof boscage bosket brake bunker buried burrow by stealth cache camouflaged canebrake cased cave ceiled ceja chamisal chaparral clandestine cloak cloaked close clouded coat coated concealed concealment coped coppice copse copsewood corner couch cover coverage covered covering covertly coverture cowl cowled cowling cranny cryptic cubby cubbyhole curtain curtained cyclone cellar dark corner delitescent den disguised dormant drape drapery dugout earth eclipsed encapsulated encapsuled encased enveloped enwrapped esoteric fallout shelter feather feathers feline filmed floored form foxhole frith funk hole furtive furtively guarded guise hackle hanging harbor harborage haven hibernating hid hidden hideaway hideout hidey hole hiding hiding place hidlings hole hole-and-corner hood hooded housed housing hugger-mugger hush-hush in a cloud in a fog in camera in eclipse in purdah in the wings incommunicado lair latent lodge loricate loricated lurking mail mantle mantled mask masked mew motte muffled mysterious mystic niche nook obfuscated obscure obscured occult occulted packaged pall paved plumage port possible potential privately privy quiet recess recondite refuge retreat roofed-in run safety zone sanctuary screen screened scummed secluded secluse secret secret place sequestered sheathed shelled shelter shield shielded shifty shroud shrouded skulking sleeping slinking slinky sly sneaking sneaky speculum stash stealthily stealthy storm cave storm cellar sub rosa submerged surreptitious surreptitiously swathed tented thicket thickset trench tunnel under an eclipse under cover under house arrest under the surface under wraps under-the-counter under-the-table undercover undercovert underground underhand underhanded underlying unknown unmanifested unobtrusive veil veiled vestment virtual walled walled-in wrapped wrapped in clouds