The term 'LEFT ON A BOAT' can be broken down into two crossword solutions: PORT (4 letters) and APORT (5 letters). PORT is a noun meaning a place on the coast where ships can dock and unload cargo. It is also used as a verb to describe the act of docking a ship at such a place. APORT is an adverb meaning towards or on the left side of a boat when facing the bow. This term is often used in nautical contexts to indicate the direction of movement or the location of something on a boat.