In actuality, there is no standardized legal definition of "military veteran" in the United States. You see, veteran benefits weren't created all at one time. They've been added one-by-one for over 200 years by Congress. Each time Congress passed a new law authorizing and creating a new veteran benefit, they included eligibility requirements for that particular benefit. Whether or not one is considered a "veteran" by the federal government depends entirely upon which veteran program or benefit one is applying for.