hollow

1. Countable

   An opening or empty space within something, or a depression in a surface.

   • The dog discovered a cavity in the ground where it could shelter from the wind.

   • The children found a shallow hollow under the tree and used it as their secret hideout.

   • There is a deep hollow at the base of this tree trunk.

2. Countable

   A valley.

   • They enjoyed taking walks in the lush green hollow.

   • The town is situated in a peaceful hollow.

   • The hollow is known for its beautiful scenery.

empty

1. C2

   Having an empty space or cavity inside.

   • They used hollow pipes to reduce the weight of the structure.

   • The sculpture is made of hollow bronze.

   • Birds often nest in the hollow parts of trees.

insincere

1. C2

   Lacking value, sincerity, or substance; not genuine or meaningful.

   • His apology sounded hollow after we learned the truth.

   • The achievement felt hollow to him since he had lost his loved one.

   • Her promises of a hopeful future seemed hollow.

sound

1. Producing a sound as if from striking an empty container; resonant and low.

   • He heard a hollow echo when he knocked on the door.

   • The old wooden floor made a hollow sound underfoot.

   • The drums reverberated in the room, creating a hollow sound.