dilute vs harden

dilute

noun
  • An animal having a lighter-coloured coat than is usual. 

verb
  • To cause the value of individual shares or the stake of a shareholder to decrease by increasing the total number of shares. 

  • To become attenuated, thin, or weak. 

  • To weaken, especially by adding a foreign substance. 

  • To make thinner by adding solvent to a solution, especially by adding water. 

adj
  • Of an animal: having a lighter-coloured coat than is usual. 

  • Having a low concentration. 

  • Weak; reduced in strength by dilution; diluted. 

harden

verb
  • To become or make (a person or thing) resistant or less sensitive. 

  • To become or make (a consonant) more fortis; to (cause to) undergo fortition. 

  • To strengthen. 

  • To make something hard or harder (tough, resistant to pressure). 

  • To modify (a website or other system) to make it resistant to malicious attacks. 

  • To unpalatalize or velarize. 

  • To become hard (tough, resistant to pressure). 

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