The word dock has several related meanings:

1. A structure built along the shore where boats and ships can tie up to load, unload, or park. When a ferry arrives at its destination, it pulls up to the dock so passengers can walk off safely. Fishermen tie their boats to docks overnight. Large cargo ships use massive docks equipped with cranes to move containers on and off. The dock serves as the meeting point between water and land, making it possible to step from solid ground onto a boat without getting wet.
2. To bring a boat or ship into a dock, or to connect two spacecraft together in orbit. A captain docks her boat carefully, making sure not to bump into the dock. Astronauts must dock their spacecraft precisely with the space station, matching speed and angle perfectly.
3. To cut off part of something, especially wages or points. A teacher might dock points from your assignment for turning it in late. An employer could dock an employee's pay for missing work. When used this way, docking usually means taking away a portion as a penalty or consequence.