What is a lee shore?
A lee shore is any shoreline that you would drift into should your vessel lose power. Most of the time this means the shoreline that is downwind of you, but it can include shorelines down current of your vessel as well.
The degree of danger that is posed to your vessel by a lee shore is directly proportional to the force of the wind and current that is pushing you toward it. If you misjudge this force and then lose power, you can be on the lee shore faster than you can anchor your boat.