Is a 18 year old a minor?

No, an 18-year-old is an adult, except in three states and a few jurisdictions. I believe they are Alabama, Nebraska, and Mississippi. I believe in certain sections of New Jersey and New York an 18-year-old will be looked at as a "minor" for certain purposes, such as buying tobacco products where one must be 19 years or older. In all states, one must be 21 years of age to consume Alcoholic Beverages, again a purpose where an 18-year-old will be looked at as a "minor".