Definitions
1.verbTo become hard (tough, resistant to pressure).
2.verbTo make something hard or harder (tough, resistant to pressure).
3.verbTo strengthen.
4.verbTo modify (a website or other system) to make it resistant to malicious attacks.
5.verbTo become or make (a person or thing) resistant or less sensitive.
6.verbTo become or make (a consonant) more fortis.
7.nounThe process by which something hardens.
8.nounThat which hardens, such as a material used for converting the surface of iron into steel.