rubber vs thermionic valve

rubber

noun
  • The cushion of an electric machine. 

  • An individual match within the series (especially in racquet sports). 

  • A coarse towel for rubbing the body. 

  • An abrasive for rubbing with: a whetstone, file, or emery cloth, etc. 

  • Water-resistant shoe covers, galoshes, overshoes. 

  • Synthetic materials with the same properties as natural rubber. 

  • An eraser. 

  • One who practises massage. 

  • A condom. 

  • The rectangular pad on the pitcher's mound from which the pitcher must pitch. 

  • One who rubs down horses. 

  • Tires, particularly racing tires. 

  • Someone or something which rubs. 

  • A rubber match; a game or match played to break a tie. 

  • The entire series, of an odd number of games or matches in which ties are impossible (especially a series of three games in bridge or whist). 

  • Pliable material derived from the sap of the rubber tree; a hydrocarbon polymer of isoprene. 

  • The game of rubber bridge. 

verb
  • To rubberneck; to observe with unseemly curiosity. 

  • To eavesdrop on a telephone call 

adj
  • Not covered by funds on account. 

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 rubber and thermionic valve occurred in a corpus of books? (source: Google Ngram Viewer )