To place (objects) into a line (usually used with "up"); to form into a line; to align.

“to line troops”

To place persons or things along the side of for security or defense; to strengthen by adding; to fortify.

“to line works with soldiers”

To form a line along.

To cover the inner surface of (something), originally especially with linen.

“The bird lines its nest with soft grass.”

To reinforce (the back of a book) with glue and glued scrap material such as fabric or paper.

To fill or supply (something), as a purse with money.

“to line the shelves”

(of a dog) To copulate with, to impregnate.

A covering for the inside surface of something.

The material used for such a covering.

The act of attaching such a covering.