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. (a) A packing of soft material round the piston of a steam engine. (b) A metallic ring for retaining a piston packing in place; (c) 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.