fixture vs thermionic valve

fixture

noun
  • A lighting unit; a luminaire. 

  • A work-holding or support device used in the manufacturing industry. 

  • A scheduled match. 

  • A regular patron of a place or institution; a person constantly present at a certain place. 

  • Something that is fixed in place, especially a permanent appliance or other item of personal property that is considered part of a house and is sold with it; compare fitting, furnishing. 

  • A state that can be recreated, used as a baseline for running software tests. 

verb
  • To furnish with, as, or in a fixture. 

  • To schedule (a match). 

thermionic valve

noun
  • An electronic device incorporating electrons from a glowing cathode inside an evacuated glass tube, functioning as a switch, amplifier etc. 

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