keystone Synonyms

anchor linchpin lynchpin mainstay foundation key cornerstone headstone key element core element pivot support backbone voussoir significance decisive factor staple building block screw wrench tombstone key fruit trapezium vault bedrock vaulting A-line wedge ground tackle coign Anchor Point vital element essential element main ingredient pivotal point corner-stone Keys foundation stone ground rule keystone species screw key critical factor key note central element arch core cotter crown crux decretion dome