|  keystone 
 
 1. 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
 • Syn:
 anchor, mainstay, backbone, linchpin, lynchpin
 • Derivationally related forms:
 anchor (for: anchor)
 • Hypernyms:
 support
 2. the central building block at the top of an arch or vault
 • Syn:
 key, headstone
 • Hypernyms:
 building block
 • Hyponyms:
 quoin, coign, coigne
 • Part Holonyms:
 arch
 
 
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