hollow

a cavity or space in something

• “hunger had caused the hollows in their cheeks”

a small valley between mountains

• “he built himself a cabin in a hollow high up in the Appalachians”

a depression hollowed out of solid matter

not solid; having a space or gap or cavity

• “a hollow wall”
• “a hollow tree”
• “hollow cheeks”
• “his face became gaunter and more hollow with each year”

deliberately deceptive

• “hollow (or false) promises”
• “false pretenses”

as if echoing in a hollow space

• “the hollow sound of footsteps in the empty ballroom”

devoid of significance or point

• “empty promises”
• “a hollow victory”
• “vacuous comments”

remove the inner part or the core of

• “the mining company wants to excavate the hillsite”

remove the interior of

• “hollow out a tree trunk”