For the labor union, see International Brotherhood of Teamsters. Teamster driving a team of six horses at the Oktoberfest in Munich, Germany. A teamster, in modern American English, is a truck driver, or a member of the International Brotherhood of Teamsters, a labor union in the United States and Canada. Originally, the term teamster referred to a person who drove a team of draft animals, usually a wagon drawn by oxen, horses, or mules.