Touchline is a term used in the field of sports, which refers to the boundary line that separates the playing field from the area designated for spectators. The term is mainly used in football, rugby, and other similarly played games. Synonyms for touchline include sideline, boundary line, perimeter line, and chalk line. The sideline marks the limit of the playing field and is used to determine whether a ball is in or out of bounds. The boundary line is a marking on the field indicating where a player is allowed to play. The perimeter line is the outermost boundary of the playing field, while the chalk line is a line drawn on the ground to delimit different sections of the field.