What is one primary ingredient in a traditional Old Fashioned cocktail?

A traditional Old Fashioned cocktail is characterized mainly by its use of a sugar cube or simple syrup, which serves as the base sweetener in the drink. This ingredient provides the necessary sweetness that balances the flavors of the other components. When making an Old Fashioned, bartenders typically muddle a sugar cube with a few dashes of bitters and a splash of water to dissolve the sugar before adding the whiskey. This foundational step creates a rich, sweet profile that enhances the overall taste of the cocktail.

While bitters are essential in an Old Fashioned, they function more as a flavoring agent rather than the primary ingredient. Club soda is not traditionally used in the classic recipe, and honey, while it can be experimented with in variations, is not a standard ingredient of the Old Fashioned. The sugar cube or simple syrup is thus the core component that defines this timeless cocktail.