"lynchpin" in the noun sense
1. anchor, mainstay, keystone, backbone, linchpin, lynchpin
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"
2. linchpin, lynchpin
pin inserted through an axletree to hold a wheel on
Source: WordNet® (An amazing lexical database of English)
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