firmness vs tenacity

firmness

noun
  • physical durability; rigidness (of material) 

  • security; steadfastness; good grip 

  • strictness; mental strength 

tenacity

noun
  • The quality of bodies which keeps them from parting without considerable force, as distinguished from brittleness, fragility, mobility, etc. 

  • The quality of bodies which makes them adhere to other bodies; adhesiveness, viscosity. 

  • The greatest longitudinal stress a substance can bear without tearing asunder, usually expressed with reference to a unit area of the cross section of the substance, as the number of pounds per square inch, or kilograms per square centimeter, necessary to produce rupture. 

  • The quality or state of being tenacious, or persistence of purpose; tenaciousness. 

  • The effect of this attraction, cohesiveness. 

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