What is a gangplank?

Answer 1

A gangplank is a board, walkway, ramp or stairs extending from a floating vessel to load or unload people and/or material. Is is still in common usage. It is not an archaic term. Here in the Mediterranean, it is often called a passerelle. Nearly every boat and yacht has at least one. I use ours daily.

In the movies and old novels, it was said to be use to send unwanted sailors to their deaths. They "walked the plank" while at sea, with nothing but air and the ocean below at the other end. Perhaps a myth, although clearly, barbaric cruelty was not rare.