Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun keystone

2 senses of keystone

Sense 1
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")
       => support -- (something providing immaterial assistance to a person or cause or interest; "the policy found little public support"; "his faith was all the support he needed"; "the team enjoyed the support of their fans")

Sense 2
keystone, key, headstone -- (the central building block at the top of an arch or vault)
       => building block -- (a block of material used in construction work)