Other forms: juniors
Use the word junior to describe things that are intended for young people, like the junior chess tournament for elementary school kids or the junior department in a clothing store, with kid-sized sweaters and jeans.
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. As a noun, a junior is in the third year of high school or college, and if you share your dad's name, he is Julio Smith and you are Julio Smith, Junior.