Glossary
Address - Taking a stance and placing the club head behind the ball
The act of taking a stance and placing the club head behind the ball. If the ball moves once a player has addressed the ball, there is a one-stroke penalty.
In common usage, "address" refers to the golfer being in position and ready to play a stroke. That is, the golfer is standing over the golf ball with his club grounded (the sole of the club is touching the turf, except, of course, in situations where grounding the club is forbidden by the rules), in position to start his swing.