What is "junk wad"

Junk \Junk\, n. [Pg. junco junk, rush, L. juncus a bulrush, of which ropes were made in early ages. Cf. Junket.]

1. Pieces of old cable or old cordage, used for making gaskets, mats, swabs, etc., and when picked to pieces, forming oakum for filling the seams of ships.

2. Old iron, or other metal, glass, paper, etc., bought and sold by junk dealers.

3. Hence: Something worthless, or only worth its value as recyclable scrap.

4. (Naut.) Hard salted beef supplied to ships. Junk bottle, a stout bottle made of thick dark-colored glass. Junk dealer, a dealer in old cordage, old metal, glass, etc. Junk hook (Whaling), a hook for hauling heavy pieces of blubber on deck. Junk ring.

   1. A packing of soft material round the piston of a steam engine.

   2. A metallic ring for retaining a piston packing in place;

   3. A follower.

      Junk shop, a shop where old cordage, and ship's tackle, old iron, old bottles, old paper, etc., are kept for sale.

      Junk vat (Leather Manuf.), a large vat into which spent tan liquor or ooze is pumped.

      Junk wad (Mil.), a wad used in proving cannon; also used in firing hot shot.