Definitions of hollow:

• noun:   a small valley between mountains

  Example: "He built himself a cabin in a hollow high up in the Appalachians"

• noun:   a cavity or space in something

  Example: "Hunger had caused the hollows in their cheeks"

• noun:   a depression hollowed out of solid matter
• verb:   remove the interior of

  Example: "Hollow out a tree trunk"

• verb:   remove the inner part or the core of
• adjective:   as if echoing in a hollow space

  Example: "The hollow sound of footsteps in the empty ballroom"

• adjective:   not solid; having a space or gap or cavity

  Example: "A hollow wall"

• adjective:   devoid of significance or point

  Example: "A hollow victory"

• adjective:   deliberately deceptive

  Example: "Hollow (or false) promises"

• name:  A surname (very rare: popularity rank in the U.S.: #22964)