hub vs linchpin

hub

noun
  • A block for scotching a wheel. 

  • A rough protuberance or projecting obstruction. 

  • A point where many routes meet and traffic is distributed, dispensed, or diverted. 

  • A goal or mark at which quoits, etc., are thrown. 

  • A computer networking device connecting several Ethernet ports. See switch. 

  • The central part, usually cylindrical, of a wheel; the nave. 

  • A central facility providing a range of related services, such as a medical hub or an educational hub. 

  • A stake with a nail in it, used to mark a temporary point. 

  • A hardened, engraved steel punch for impressing a device upon a die, used in coining, etc. 

  • A screw hob. 

  • An area in a video game from which individual levels are accessed. 

  • A male weasel; a buck; a dog; a jack. 

linchpin

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

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

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

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