The term starboard orginates from an Old Norse word meaning "steerboard". Viking ships were steered not with a rudder but with a broad steering oar on the right side of the ship.
Because the steering oar was on the right, when the ship was docked it was tied to the dock from its left side. The term larboard was used for this "loading side" until it was decided by the British navy that larboard sounded too similar to starboard. The left side of a boat was named "port" since it's the side you tie up to, when the ship is in port.