Source : Webster's Revised Unabridged Dictionary (1913)

Mackintosh \Mack"in*tosh\, n.
   A waterproof outer garment; -- so called from the name of the
   inventor.

Source : WordNet®

mackintosh
     n 1: a lightweight waterproof (usually rubberized) fabric [syn: {macintosh}]
     2: a waterproof raincoat made of rubberized fabric [syn: {macintosh},
         {mac}, {mack}]