Final answer:
A 1 1/2 oz. shot of 86 proof liquor refers to a measurement of volume and alcohol content, where 86 proof indicates the liquor is 43% ethanol by volume.
Step-by-step explanation:
A 1 1/2 oz. shot of 86 proof liquor is a measurement of volume and alcohol content. Specifically, 'proof' is a measure of the strength of alcohol, with 86 proof indicating that the liquor contains 43% ethanol by volume. Therefore, a 1 1/2 oz. shot contains the equivalent alcohol content as a 1.5 oz. volume of 43% ethanol solution. However, the original question seems to be incomplete as it ends with 'equates________.' If the question were asking for the alcohol content or the conversion to another unit, further information would be necessary to complete the conversion.