[n] - a short plaid coat made of made of thick woolen material 2. [n] - a thick plaid blanket formerly used in NW US 3. [n] - a flat-bottomed boat used on upper Great Lakes 4. [n] - a heavy woolen cloth heavily napped and felted, often with a plaid design Found on http://www.webdictionary.co.uk/definition.php?query=mackinaw
A boat approximately 40 feet long, 10 feet across the beam, and 4 feet deep, pointed at both ends. This boat, widely used on the Mississippi, Missouri, and Ohio River systems, was capable of holding a cargo of approximately 10 tons. Often these were used for downstream travel only.
Found on http://www.xmission.com/~drudy/amm/gloss.html