Filling

Part of speech: noun (n.)

1. That which is used to fill a cavity or any empty space, or to supply a deficiency; as, filling for a cavity in a tooth, a depression in a roadbed, the space between exterior and interior walls of masonry, the pores of open-grained wood, the space between the outer and inner planks of a vessel, etc.

2. The woof in woven fabrics.

3. Prepared wort added to ale to cleanse it. Back filling. (Arch.) See under Back, a.