[n] (British) a waterproof raincoat made of rubberized fabric [n] a lightweight waterproof (usually rubberized) fabric
More below...
mac, macintosh, mack
cloth, fabric, mackintosh, material, oilskin, raincoat, slicker, textile, waterproof
\Mack"in*tosh\, n. A waterproof outer garment; -- so called from the name of the inventor.