The term starboard derives from the Old English steorbord, meaning the side on which the ship is steered. Before ships had rudders on their centrelines, they were steered with a steering oar at the stern of the ship on the right hand side of the ship, because more people are right-handed.
Larboard is from Middle English ladebord and the term lade is related to the modern load. The two words were easily confused. It would not do for a shouted command to be misinterpreted, so a different word was required. The term port for the left-hand side of a ship dates to the 16th century, but it was not until the 1840s that the Royal Navy officially abandoned the term larboard in favor of port. The United States Navy followed suit in 1846.
Why port was chosen is not known for certain, but most believe, like in larboard, it is because the left-hand side of a ship was the side typically put next to the wharf.
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