Get ready for an education on classic school-year labels. Here's how the terms freshman, sophomore, junior and senior got their start. Borrowed from Latin junior, a contraction of iuvenior (“ younger ”) which is the comparative of iuvenis (“ young ”); see juvenile. The meaning of JUNIOR is less advanced in age : younger —used chiefly to distinguish a son with the same given name as his father. How to use junior in a sentence. He was born in April, so he’s three months my junior (= he is three months younger). We define junior members as those elected fewer than four times and senior members are those elected four or more times. The participants belonged to a class of about 100 student teachers who did their internships at local junior and senior high schools. JUNIOR definition: younger (designating the younger of two men bearing the same full name, as a son named after his father; often written as Jr. or jr. following the name). See examples of junior used in a sentence. 1. A person who is younger than another: a sister four years my junior. 2. A person lesser in rank or time of participation or service; subordinate. 3. A student in the third year of a US high school or college. 4. A class of clothing sizes for girls and slender women. Also called junior miss. Junior: Directed by Ivan Reitman. With Arnold Schwarzenegger, Danny DeVito, Emma Thompson, Frank Langella. As part of a fertility research project, a male scientist agrees to carry a pregnancy in his own body. Junior is used to mean younger, so you might describe your cousin as being six years your junior. It also means lower in rank, so new representatives in Congress are often called junior members, and workers are described as junior to others higher in the company hierarchy. If you are someone's junior, you are younger than they are. She had fallen in love with a truck driver ten years her junior.