The position of "first mate" is an important one, as it is the second-in-command on a ship and has significant responsibilities. However, there are a variety of other terms that can be used as synonyms for this role. Some options include "chief mate," "second officer," "senior deck officer," and "executive officer." Each of these terms emphasizes different aspects of the first mate's job and can be used interchangeably depending on the context. No matter what the title is, the first mate is an essential member of any ship's crew and plays a crucial role in ensuring that the vessel operates smoothly and safely.