a. [ L. contr. fr. juvenior, compar. of juvenis young. See Juvenile. ] [ 1913 Webster ]

1. Less advanced in age than another; younger. Abbreviated Jr. [ 1913 Webster +PJC ]

☞ Junior is applied to distinguish the younger of two persons bearing the same name in the same family, and is opposed to senior or elder. Commonly applied to a son who has the same Christian name as his father. [ 1913 Webster ]

2. Lower in standing or in rank, or having entered later into a position or office; as, a junior partner; junior counsel; junior captain; the junior Senator from New York. [ 1913 Webster ]

3. Composed of juniors, whether younger or a lower standing; as, the junior class; the junior baseball league; of or pertaining to juniors or to a junior class. See Junior, n., 2. [ 1913 Webster ]

4. Belonging to a younger person, or an earlier time of life. [ 1913 Webster ]

Our first studies and junior endeavors. Sir T. Browne. [ 1913 Webster ]

5. of or relating to the third year of a four-year term; -- used of the third or next to final year in a U. S. high school or college. See junior{ 2 }, n..
Syn. -- third-year. [ WordNet 1.5 +PJC ]

n. 1. A younger person. [ 1913 Webster ]

His junior she, by thirty years. Byron. [ 1913 Webster ]

2. Hence: One of a lower or later standing; specifically, in American colleges and four-year high schools, one in the third year of his course, one in the fourth or final year being designated a senior; in some seminaries, one in the first year, in others, one in the second year, of a three years' course. [ 1913 Webster ]

n. The state or quality of being junior. [ 1913 Webster ]