A line that runs the length of the pitch and marks the side boundary.

The line surrounding the field of play, made up of the sidelines and the end-lines.

either of the sidelines in soccer or Rugby

The boundary lines on the long sides of the field.

The line that defines the side of the playing field. Note - the touchline is part of the field.

The lines that mark the side boundaries of the field and are considered part of the field.

The touchline is the sideline. If you hear someone say that the ball "goes into the touch" it means that it is just out of bounds.

see Sideline.