adjective
(comparable) Low in rank; having a subordinate role, job, or situation.
(not comparable, often preceded by a possessive adjective or a possessive form of a noun) Younger.
(not comparable) Belonging to a younger person, or an earlier time of life.
(not comparable, chiefly US) Of or pertaining to a third academic year in a four-year high school (eleventh grade) or university.
(not comparable, chiefly UK, Ireland, Commonwealth) Of or pertaining to the latter half of primary school education.
(sports, US, Canada) Of or pertaining to a league or competition limited to players below a certain age or level of experience.
noun
(countable) A younger person.
A name suffix used after a son's name when his father has the same name (abbreviations: Jnr., Jr., Jun.).
(uncountable) A clothing size for girls or women.
(countable, chiefly US, Philippines) A third-year student at a high school or university.
(countable, chiefly UK, Ireland, Commonwealth) A student in a junior school or the second part of a primary school.
(countable, law) A junior barrister.
verb
(ambitransitive) To work in a junior role (on something).
(transitive) To have juniors (more advanced students) assist in instructing (beginners).