Junior describes someone or something that is younger, lower in rank, or less experienced than others in the same group. A junior doctor has just finished medical school and is still learning from more experienced physicians. A junior member of a debate team might be in their first or second year, while senior members have competed for longer.

In American schools, a junior is a student in the third year of high school or college. The progression goes freshman, sophomore, junior, senior: each year brings you closer to graduation, and juniors often start thinking about their futures.

Parents sometimes add “Junior” (often abbreviated as “Jr.”) to a son's name when a father and son share the exact same name. Martin Luther King Jr. carried his father's name, as did John F. Kennedy Jr. This tradition helps distinguish between two people in the same family with identical names.

The word can also describe smaller or younger versions of things: a junior tennis racket is sized for children, and a junior burger is smaller than the regular size. In workplaces, a junior position means you're earlier in your career, learning the ropes before advancing to more responsibility.