The term 'One Who Crosses a Line' can be summarized as a SCAB, which is a four-letter word. A SCAB is someone who takes the job of a striking worker, thus crossing the line between the two sides. This term is often used in labor disputes, where one side is striking and the other side is hiring new workers to replace them. Scabs are seen as traitors by the striking workers, as they are taking away their jobs and undermining their efforts.