D defs.my
Entry 2 senses Webster, 1913

Bluing

/blo͞o'-ĭng/ · Blu·ing · IPA /blˈuːɪŋ/
01 n. The act of rendering blue; as, the bluing of steel.
  1. 1.
    The act of rendering blue; as, the bluing of steel.
  2. 2.
    Something, as indigo or other preparations, used to give a bluish tint, especially to white clothing when being washed.