hardening

/HH AA1 R D AH0 N IH0 NG/
verb
  1. 1

    To become hard (tough, resistant to pressure).

  2. 2

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

  3. 3

    To strengthen.

  4. 4

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

  5. 5

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

    syn:inure
  6. 6

    To become or make (a consonant) more fortis.

Synonyms

noun
  1. 1

    The process by which something hardens.

  2. 2

    That which hardens, such as a material used for converting the surface of iron into steel.

Source: https://en.wiktionary.org/wiki/harden, https://en.wiktionary.org/wiki/hardening