1. [n]  the younger of two men
2. [n]  a third-year undergraduate
3. [n]  a son who has the same first name as his father
4. [n]  term of address for a disrespectful and annoying male; "look here, junior, it's none of your business"
5. [adj]  including or intended for youthful persons; "a junior sports league"; "junior fashions"
6. [adj]  younger; lower in rank; shorter in length of tenure or service

Junior
What happens when Arnold Schwarzenegger gets pregnant? The hilarious answer is delivered in this delightful comedy from Ivan Reitman, the director of Ghostbusters and Twins. Co-starring Danny DeVito and Academy Award winner Emma Thompson, it?s a radiant, laugh-inducing farce that touches the heart as deftly as it tickles the funnybone. Schwarzenegger portrays Dr. Alex Hesse, who with his associate, Dr. Larry Arbogast (DeVito), has developed a wondrous new drug to ensure healthy pregnancies. But when the government forbids further testing of their creation, Alex and Larry secretly move forward with a daring plan. To succeed, they must cope with a snooping, villainous research administrator (Frank Langella) and the brilliant, beautiful-but-klutzy scientist, Dr. Diana Reddin (Thompson). The seeds are sown for a hysterical, high-spirited whirlwind of humor, romance and tender insights into the magnificent power of maternal love.

more details ...

1. \Jun"ior\, a. [L. contr. fr. juvenior, compar. of juvenis
   young. See {Juvenile}.]
   1. Less advanced in age than another; younger.
   Note: 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; later in office; as, a
      junior partner; junior counsel; junior captain.
   3. Composed of juniors, whether younger or a lower standing;
      as, the junior class; 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.
   

2. \Jun"ior\, n.
   1. A younger person.
            His junior she, by thirty years.      -- Byron.
   2. Hence: One of a lower or later standing; specifically, in
      American colleges, 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.