A cushioning material placed under carpeting to provide support, insulation, and reduce noise.

To be positioned or situated beneath something else; to provide a base or foundation for something.

To serve as the foundation or support for something, typically underlying or forming the base for it.

To underlay is to place a base or support underneath something to provide stability or reinforcement.

To place something underneath or beneath another object or surface.

To insert a piece of paper or cardboard under the type to raise or support the level of printing.