Jr, an abbreviation commonly used in the United States to denote a person with the same name as their father but is younger. Synonyms for Jr can include Second, II, the younger, and junior. These terms are often used interchangeably, but generally, Second is used for those who have the same name as their fathers and have a different middle name. II is used for those who have the same name as their fathers, with the same middle name, while junior is used for those who have the same name as their fathers but are younger. Although these terms may vary, they all represent the unique identity of an individual within their family line.