Webster's Revised Unabridged Dictionary · 1913

Junior

Junior (jūn"yẽr; 277) , adjective

[Latin contr. from juvenior, compar. of juvenis young. See Juvenile.]

1.
Less advanced in age than another; younger. Abbreviated Jr.

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.

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.
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.
4.
Belonging to a younger person, or an earlier time of life.
Our first studies and junior endeavors. — Sir T. Browne
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..

Junior , noun

1.
A younger person.
His junior she, by thirty years. — Byron
2.
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.