"Hole" can refer to two different things when used as a noun:
1. The point on the green where the flagstick stands and where turf and sod have been removed to create the "hole" into which the player putts. In other words, the hole is literally the hole in the putting green.
The hole on the green is 4.25 inches in diameter, and is at least four inches deep according to the rules.
2. One of the units of play on a golf course: That area from the teeing ground, down the fairway and to the putting green constitutes one hole. There are 18 such holes on a regulation golf course.
As a verb: Tiger Woods really needs to hole this putt.

