n.

1. a cavity or space in something
   
   • hunger had caused the hollows in their cheeks
2. a small valley between mountains;
   holler
   
   • he built himself a cabin in a hollow high up in the Appalachians
3. a depression hollowed out of solid matter;
   hole

v.

1. remove the inner part or the core of;
   excavate, dig
   
   • the mining company wants to excavate the hillside
2. remove the interior of;
   hollow out, core out
   
   • hollow out a tree trunk

adj.

1. 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
2. deliberately deceptive;
   false
   
   • hollow (or false) promises
   • false pretenses
3. as if echoing in a hollow space
   
   • the hollow sound of footsteps in the empty ballroom
4. devoid of significance or point;
   empty, vacuous
   
   • empty promises
   • a hollow victory
   • vacuous comments