custodian vs keyholder

custodian

noun
  • A person entrusted with the custody or care of something or someone; a caretaker or keeper. 

  • a janitor; a cleaner 

keyholder

noun
  • One who holds the key to a building etc. for security reasons. 

  • A device or component for holding a key. 

  • The individual or organisation with access to a cryptographic key. 

  • A dominant partner who controls whether their submissive partner is able or allowed to orgasm or receive sexual stimulation, typically by locking the submissive partner in a chastity belt or chastity cage. 

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