Sealed adjective – Closed or secured with or as if with a seal. Tight is a synonym for sealed in state topic. In some cases you can use "Tight" instead an adjective "Sealed", when it comes to topics like secured. Nearby Words: seal, sealing, sealer
Since their service deals with Eldritch Abominations on a regular basis, an insane necromantic scientist is a bit of a security risk; hence the building is sealed off tight from the outside world and insulated in every form imaginable.
The Legend of Zelda's Hyrule suffers this chronically, albeit not on a very tight schedule with Ganondorf/Ganon being repeatedly sealed and escaping or dying and reviving/being reborn exactly the same.