- 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"
--1 is a kind of support
- linchpin, lynchpin - pin inserted through an axletree to hold a wheel on
--2 is a kind of pin