DRAM vs trapdoor

DRAM

noun
  • Dynamic random access memory. 

trapdoor

noun
  • A secret method of obtaining access to a program or online system; a backdoor. 

  • The special information that permits the inverse of a trapdoor function to be easily computed. 

  • Such a trap set into the floor of a stage to allow fast exits and entrances. 

  • A door in a level for regulating the ventilating current; a weather door. 

  • A hinged or sliding door set into a floor or ceiling. 

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