lynchpin

Noun lynchpin has 2 senses

• lynchpin(n = noun.cognition) anchor, backbone, keystone, linchpin, mainstay - 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"
is a kind of support

• lynchpin(n = noun.artifact) linchpin - pin inserted through an axletree to hold a wheel on;
is a kind of pin