line

A line is a mark that is long, straight and very thin.

Example: She drew a line down the middle of the page to divide the page into two parts.

A line is a row.

Example: Put the buttons in a straight line on the front of the shirt.

A line is a row of people who are waiting for something in order; a queue.

Example: You got here last, so you have to stand at the back of the line.

Someone lines things up when they put them in a straight line or row.

Someone lines something up when they put it just in the right place or at the edge of something.

Example: Line up the end of the piece of wood with the edge of the table.