'Mainstay' definitions:

Definition of 'mainstay'

(from WordNet)
noun
A prominent supporter; "he is a pillar of the community" [syn: pillar, mainstay]
noun
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, keystone, backbone, linchpin, lynchpin]
noun
The forestay that braces the mainmast

Definition of 'Mainstay'

From: GCIDE
  • Mainstay \Main"stay`\, n.
  • 1. (Naut.) The stay extending from the foot of the foremast to the maintop. [1913 Webster]
  • 2. Main support; principal dependence. [1913 Webster]
  • The great mainstay of the Church. --Buckle. [1913 Webster]