What is "soft patch"

Patch \Patch\, n. [OE. pacche; of uncertain origin, perh. for placche; cf. Prov. E. platch patch, LG. plakk, plakke.]

1. A piece of cloth, or other suitable material, sewed or otherwise fixed upon a garment to repair or strengthen it, esp. upon an old garment to cover a hole.

   Patches set upon a little breach.
   --Shak.

2. Hence: A small piece of anything used to repair a breach; as, a patch on a kettle, a roof, etc.

3. A small piece of black silk stuck on the face, or neck, to hide a defect, or to heighten beauty.

   Your black patches you wear variously.
   --Beau. & Fl.

4. (Gun.) A piece of greased cloth or leather used as wrapping for a rifle ball, to make it fit the bore.

5. Fig.: Anything regarded as a patch; a small piece of ground; a tract; a plot; as, scattered patches of trees or growing corn.

   Employed about this patch of ground.
   --Bunyan.

6. (Mil.) A block on the muzzle of a gun, to do away with the effect of dispart, in sighting.

7. A paltry fellow; a rogue; a ninny; a fool. [Obs. or Colloq.] ``Thou scurvy patch.''
   --Shak.

   Patch ice, ice in overlapping pieces in the sea.

   Soft patch, a patch for covering a crack in a metallic vessel, as a steam boiler, consisting of soft material, as putty, covered and held in place by a plate bolted or riveted fast.