Liner \Lin"er\ (l[imac]n"[~e]r), n.

1. One who lines, as, a liner of shoes.

2. A vessel belonging to a regular line of packets; also, a line-of-battle ship; a ship of the line.

3. (Mach.) A thin piece placed between two parts to hold or adjust them, fill a space, etc.; a shim.

4. (Steam Engine) A lining within the cylinder, in which the piston works and between which and the outer shell of the cylinder a space is left to form a steam jacket.

5. A slab on which small pieces of marble, tile, etc., are fastened for grinding.

6. (Baseball) A ball which, when struck, flies through the air in a nearly straight line not far from the ground.

Source: Webster's Revised Unabridged Dictionary (1913)