English noun: keystone
|1.||keystone (cognition) a central cohesive source of support and stability|
|Samples||Faith is his anchor.|
The keystone of campaign reform was the ban on soft money.
He is the linchpin of this firm.
|Synonyms||anchor, backbone, linchpin, lynchpin, mainstay|
|2.||keystone (artifact) the central building block at the top of an arch or vault|
|Broader (hypernym)||building block|
|Narrower (hyponym)||coign, coigne, quoin|