What is the definition of a "highball" in bartending?

A highball in bartending refers to a mixed drink that is typically served in a tall glass. This category encompasses various combinations of a spirit and a non-alcoholic mixer, such as soda or tonic water. The tall glass ensures there is ample space for the mixer, allowing the drink to be refreshing and easy to sip. Highballs usually have a simple, straightforward presentation, focusing on the balance between the spirit and the mixer.

The other options do not capture the essence of what a highball is. For instance, serving a spirit straight does not involve any mixer, which distinguishes it from a highball. Similarly, while cocktails made with rum may fall into the broader category of mixed drinks, the term "highball" specifically refers to the type of glass and presentation, which is not limited to any single type of spirit. Finally, a drink served with ice alone does not fulfill the criteria of a highball, as there must be a mixer involved to provide the characteristic combination that defines this drink.