Polyandria is an archaic word (no longer used) for an ancient tomb or subterranean mass burial site. In neotoy however the word is used to describe the lowest habitable layer of the undermetto
.. although "habitable" might be a bit misleading since there are several extreme environmental factors unique to the level that make it the kind of place you wouldn't want to go on vacation. First the temperature is more or less consistently 0 K, a.k.a. absolute zero; making it only navigable (reliably) via quantum mechanical zero-point energy. Second due to its proximity to the core of the planet the gravity is greatly reduced while the pressure is greatly increased.
In the beginning of neotoy the first living beings grew tired to living so they eventually made their way to polyandria where they sleep, waiting for something that will renew their interest in the universe.