A "position line" is a navigational term used to describe a line on a map or chart that indicates the possible locations of a vessel, aircraft, or object. Synonyms for "position line" include "bearing line," "range line," and "fix line." A "bearing line" is a line that represents the direction from an observer to a certain object. "Range line" is a line that indicates the distance from the observer to the object. Lastly, a "fix line" is a line that shows where a vessel or aircraft is located based on the intersection of two or more bearing or range lines. All of these terms are commonly used in marine and aviation navigation, helping pilots and sailors to determine their position and whereabouts while on the move.