What DrinkBoy says may well be true. Old Fashioned may simply have meant a whiskey prepared in the "old" way. That was with a little sweetener (gum syrup, simple syrup, orgeat, etc), some bitters, the whiskey, ice, and maybe a lemon peel garnish.
Cocktail Boothby's American Bar-Tender (1895) lists just such a cocktail as a whiskey cocktail.
Cheryl Lins - Proprietor and distiller, Delaware Phoenix Distillery, Walton, NY