Crewman is a generic term for a crew member of an aircraft, naval vessel, military unit, or team of professionals attempting to accomplish a goal. In some science fiction (most notably Star Trek), crewman is the lowest military rank on board a spacecraft, analogous to seaman in many real world navies. The term "crewman" may also be used interchangeably with the non-gender specific form as "crewperson" or "crewmember".