Definitions of soften:

• verb:   make (images or sounds) soft or softer
• verb:   become soft or softer

  Example: "The bread will soften if you pour some liquid on it"

• verb:   make soft or softer

  Example: "This liquid will soften your laundry"

• verb:   make less severe or harsh
• verb:   give in, as to influence or pressure
• verb:   lessen in force or effect

  Example: "Soften a shock"

• verb:   protect from impact