buttress vs linchpin

buttress

noun
  • Anything that serves to support something; a prop. 

  • A brick or stone structure built against another structure to support it. 

  • Anything that supports or strengthens. 

  • A buttress-root. 

  • A feature jutting prominently out from a mountain or rock. 

verb
  • To support something or someone by supplying evidence. 

  • To support something physically with, or as if with, a prop or buttress. 

linchpin

noun
  • A central cohesive source of stability and security; a person or thing that is critical to a system or organisation. 

  • A pin inserted through holes at the end of an axle or shaft, so as to secure a wheel or shaft-mounted device. 

verb
  • To adopt as, or serve as, a central cohesive source of stability and security. 

How often have the words buttress and linchpin occurred in a corpus of books? (source: Google Ngram Viewer )