An alternative translation is "He Who Glares," or "The Glowering One."
The Burdinadin are the most aware of this entity, that dwells in the deep and eternal void into which their consciousnesses probe when using their Natural Philosophy to penetrate worldly secrets. That Which Stares Back is a presence in that infinite realm, always distant, yet always watching, an eye amidst a sea of churning shapes. A questioning Burdinadin must always be careful not to look into the thing's great eye, for each glance brings it closer, and closer it will forever stay, until each trip into the void brings one into its horrible staring orbit, clawed tentacles flailing in the silent vacuum.
This obviously makes it a bit harder to concentrate on figuring out the function of an alembic, or whatever. A few brave Burdinadin have tried to analyze That Which Stares Back using Natural Philosophy. Results range from brain-death to the corporeal body of the courageous scientist being sucked out of the material world through his own eye sockets, vanishing in a scream of terror and a crunching of powdered bones.
Other peoples are also aware of the great entity. Thaumaturges call it "The Final Bargain," an entity with whom only one deal can be made, and certain human cults, who witness it through the use of hallucinatory drugs and ritual, call it "The Eye" and revere it in secret.
Whatever the powers of this alien creature, it does have its limits. For in the great pressure chambers in the depths of the sea, for example in Glade Lata, which extends beneath a great lighthouse to nearly a thousand feet below sea-level, it is said that That Which Stares Back can no longer be seen. There, a small cadre of fearless acclimated Burdinadin huddle in the flickering artificial light, probing the secrets of the void.