hardness vs tool

hardness

noun
  • The quality of being hard. 

  • An instance of this quality; hardship. 

  • The resistance to scratching, cutting, indentation or abrasion of a metal or other solid material. 

  • The penetrating ability of electromagnetic radiation, such as x-rays; generally, the shorter the wavelength, the harder and more penetrating the radiation. 

  • The measure of resistance to damage of a facility, equipment, installation, or telecommunications infrastructure when subjected to attack. 

  • A measure of how hard a material is 

  • The quantity of calcium carbonate dissolved in water, usually expressed in parts per million (ppm). 

tool

noun
  • A mechanical device intended to make a task easier. 

  • A penis, notably with a sexual or erotic connotation. 

  • A person or group which is used or controlled, usually unwittingly, by another person or group. 

  • Something to perform an operation; an instrument; a means. 

  • Any piece of equipment used in a profession, e.g. a craftman's tools. 

  • A gun. 

  • A piece of software used to develop software or hardware, or to perform low-level operations. 

  • An obnoxious or uptight person. 

verb
  • To equip with tools. 

  • To work on or shape with tools, e.g., hand-tooled leather. 

  • To work very hard. 

  • To intentionally attack the ball so that it deflects off a blocker out of bounds. 

  • To travel in a vehicle; to ride or drive. 

  • To put down another person (possibly in a subtle, hidden way), and in that way to use him or her to meet a goal. 

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