the most important part, from the idea of the central stone in an arch that keeps the other stones in position - without it, the whole arch would fall down
A keystone of a policy, system, or process is an important part of it, which is the basis for later developments. Keeping inflation low is the keystone of their economic policy
a stone of the crown string course of an arch; the final stone placed, closing the arch; or symmetrically shaped, wedge-like stone in a head-ring course at the crown of the arch, extending beyond the extradosal and intradosal limits of the voussoirs of adjoining string courses
Distortion of a projected image in which the top of the image looks broader than the bottom caused by the difference in the distance from the top of image to projector lens as compared to the space between the bottom of the image and the lens
Keystone (kê´ston´) noun 1) The stone at the top or middle of an arch or vault, which, being wider at the top than at the bottom, enters like a wedge and binds the work; sometimes being projecting and ornamented 2) In a system, that which holds the several parts together; the supporting fact or principle
a central cohesive source of support and stability; "faith is his anchor"; "the keystone of campaign reform was the ban on soft money"; "he is the linchpin of this firm"
Each Asytryne requires a keystone for operation The keystone contains the self-contained Attistar for a specific Asytryne, and typically one keystone can only operate the Asytryne it was designed for A keystone Attistar contains all of the security coded hyperwave pattern "ports" needed to interface with the many sub-systems of its Asytryne Some "master" keystones may exist which have the ability to "hack" into the ports of any Asytryne, but these are rare, and even in the best cases they will not be able to operate an Asytryne as well as the keystone AI that was designed for that Asytryne