keystone   (TTS Sound)

The noun keystone has 2 senses

• 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")


• keystone, key, headstone -- (the central building block at the top of an arch or vault)