fastness vs stronghold

fastness

noun
  • A fortified or secure place; a fortress, a stronghold. 

  • The ability of a dye to withstand fading. 

  • The quality or state of moving quickly; quickness, rapidity, swiftness. 

  • Something used to fasten or tie; a fastener or fastening. 

  • The quality or state of being strongly attached; firmness, secureness, tenacity. 

  • The quality or state of having an extravagant lifestyle or immoral habits. 

stronghold

noun
  • A place built to withstand attack; a fortress. 

  • A place of domination by, or refuge or survival of, a particular group or idea. 

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