What is the meaning of hollow?

noun

• A cavity or space in something.
  • usage: "hunger had caused the hollows in their cheeks"
• A small valley between mountains.
  • usage: "he built himself a cabin in a hollow high up in the Appalachians"
  • synonyms: holler
• A depression hollowed out of solid matter.
  • synonyms: hole

verb

• Remove the inner part or the core of.
  • usage: "the mining company wants to excavate the hillside"
  • synonyms: excavate, dig
• Remove the interior of.
  • usage: "hollow out a tree trunk"
  • synonyms: hollow out, core out

adjective

• Not solid; having a space or gap or cavity.
  • usage: "a hollow wall"; "a hollow tree"; "hollow cheeks"; "his face became gaunter and more hollow with each year"
• As if echoing in a hollow space.
  • usage: "the hollow sound of footsteps in the empty ballroom"
• Devoid of significance or point.
  • usage: "empty promises"; "a hollow victory"; "vacuous comments"
  • synonyms: empty, vacuous