glow vs thermionic valve

glow

noun
  • The light given off by a glowing object. 

  • The condition of being passionate or having warm feelings. 

  • The brilliance or warmth of color in an environment or on a person (especially one's face). 

verb
  • To be related to or part of an (chiefly online) undercover sting operation, especially by American federal agencies. 

  • to create a threatening online post that may involve violence, and look suspicious enough to attract a police investigation. 

  • To shine brightly and steadily. 

  • To emit light as if heated. 

  • To gaze especially passionately at something. 

  • to expose someone to the authorities. 

  • To display intense emotion. 

  • To make hot; to flush. 

  • To feel hot; to have a burning sensation, as of the skin, from friction, exercise, etc.; to burn. 

  • To radiate thermal heat. 

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