The Collaborative International Dictionary of English v.0.48:

Damascus steel \Da*mas"cus steel\
   See Damask steel, under Damask.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Damask \Dam"ask\, a.
   1. Pertaining to, or originating at, the city of Damascus;
      resembling the products or manufactures of Damascus.
      [1913 Webster]

   2. Having the color of the damask rose.
      [1913 Webster]

            But let concealment, like a worm i' the bud,
            Feed on her damask cheek.             --Shak.
      [1913 Webster]

   Damask color, a deep rose-color like that of the damask
      rose.

   Damask plum, a small dark-colored plum, generally called
      damson.

   Damask rose (Bot.), a large, pink, hardy, and very fragrant
      variety of rose (Rosa damascena) from Damascus. "Damask
      roses have not been known in England above one hundred
      years." --Bacon.

   Damask steel, or Damascus steel, steel of the kind
      originally made at Damascus, famous for its hardness, and
      its beautiful texture, ornamented with waving lines;
      especially, that which is inlaid with damaskeening; --
      formerly much valued for sword blades, from its great
      flexibility and tenacity.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Damascus \Damascus\ prop. n. (Geography)
   The capital city of Syria. Population (2000) = 1,549,932.
   [PJC]

   Damascus blade, a sword or scimiter, made chiefly at
      Damascus, having a variegated appearance of watering, and
      proverbial for excellence.

   Damascus iron, or Damascus twist, metal formed of thin
      bars or wires of iron and steel elaborately twisted and
      welded together; used for making gun barrels, etc., of
      high quality, in which the surface, when polished and
      acted upon by acid, has a damask appearance.

   Damascus steel. See Damask steel, under Damask, a.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Damascus steel
    n 1: a hard resilient steel often decorated and used for sword
         blades [syn: Damascus steel, Damask steel]