Final answer:
In the context of distilled spirits, 'proof' refers to the alcoholic strength, expressed as twice the percentage of alcohol present. For example, 80 proof vodka contains 40.0% ethanol by volume.
Step-by-step explanation:
In the context of distilled spirits, the term 'proof' refers to the alcoholic strength of the drink. It is expressed as twice the percentage of alcohol present in the beverage. For example, if a distilled spirit is labeled as 80 proof, it means that it contains 40.0% alcohol by volume.
An example to further illustrate this concept is vodka, which is typically sold as '80 proof' or 40.0% ethanol by volume. This means that for every 100 mL of vodka, there are 40 mL of ethanol.
Please note that the term 'proof' is specific to alcoholic beverages and is not used in other scientific contexts.