Port is the left side of a ship, starboard the right side as viewed by someone on the boat looking towards the bow. The words are in use, including in aviation, to avoid confusion. Port and starboard are always on the same side. Left and right are affected by the location of the viewer. If a ship has two bows, for example a ferry, then the rule to follow is that the bow is located at the end pointing towards the location the ship is navigating to.
A ship has a different colored navigation lights on each side. Green to starboard and red to port. These make clear which ship has right of way when visibility is low. If another boat only sees the green light he nows he can continue past the ship. If only the red light is visible, it has to give way to the other ship.
The words originate from the Vikings. In Old Norse the words bake and stýri mean back and steering wheel. As the wheel of their ships was always on the right, it was starboard. (Starboard came from the Anglo-Saxon word steorbord). Bæcbord, the side where the helmsman stood with his back to the rudder control. Bæcbord was replaced by larboard in the Middle Ages, probably derived from laddebord which means loading side. The word port was also often used and replaced larboard in 1867 according to Admiral Smyth’s “The Sailor’s Word Book”. The reason being, that larboard and starboard sound to similar.