Definitions of broaden:

• verb:   become broader

  Example: "The road broadened"

• verb:   make broader

  Example: "Broaden the road"

• verb:   extend in scope or range or area

  Example: "Broaden your horizon"

• verb:   vary in order to spread risk or to expand
• name:  A surname (very rare: popularity rank in the U.S.: #20363)