Hole

A hole is an empty space in a solid object, which can be flat.

It can also mean other things:

In golf, it is a special place on a golf course. All players want to put their ball in the holes, in as few strikes as possible.
Holes, a book written by Louis Sachar
Hole (band) was an American rock band. Their singer was Courtney Love.
Hole, Norway a municipality in Buskerud county.