hollow

remove the inner part or the core of

a small valley between mountains

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

remove the interior of

“hollow out a tree trunk”

devoid of significance or force

“a hollow victory”

a depression hollowed out of solid matter

a cavity or space in something

“hunger had caused the hollows in their cheeks”

as if echoing in a hollow space

“the hollow sound of footsteps in the empty ballroom”

lacking in substance or character

“a hollow person”

not solid; having a space or gap or cavity

“a hollow wall”