Noun

1. An unoccupied space where something may be stored

   You can park your car in that empty space.

   You can put the key in that empty space.

2. An unoccupied area or volume.

   The empty space at the sides of the page is called the "margin".

   He spends all his time staring into empty space.

3. Vacuum; a space containing nothing at all

   Atoms are 99.999999999999% empty space.