lamp vs thermionic valve

lamp

noun
  • A device that generates heat, light or other radiation. Especially an electric light bulb. 

  • A device containing oil, burnt through a wick for illumination; an oil lamp. 

  • A piece of furniture holding one or more electric light sockets. 

verb
  • To hunt at night using a lamp; see lamping. 

  • To make into a table lamp, said of a vase or urn, etc. 

  • To hang out or chill; to do nothing in particular. 

  • To hit, clout, belt, wallop. 

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