[n] the forestay that braces the mainmast
[n] a central cohesive source of support and stability; "faith is his anchor"; "he is the linchpin of this firm"
[n] a prominent supporter; "he is a pillar of the community"
1. (Naut.) The stay extending from the foot of the foremast to the maintop.
2. Main support; principal dependence. The great mainstay of the Church. --Buckle.