mainstay

Noun

• the forestay that braces the mainmast

• 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
    

• a prominent supporter
  • he is a pillar of the community
    

Related words

• Synonyms: 
  anchor , keystone , backbone , linchpin , lynchpin , pillar