light·weight 
(lītwāt′)
(lītwāt′)n.
1. One that weighs relatively little or less than average.
2.
a. A weight division in professional boxing having an upper limit of 135 pounds (60.7 kilograms), between junior lightweight and junior welterweight.
b. A boxer competing in this weight division.
c. A similar weight division in other sports, such as weightlifting.
d. A contestant in this weight division.
3. A person of little ability, intelligence, influence, or importance.
adj.
1. Weighing relatively little; not heavy: lightweight clothing; a lightweight wood.
2. Sports Of, relating to, or characteristic of a lightweight: the lightweight title.
3. Having no significance or influence: a lightweight intellect.