fly·weight 
(flīwāt′)
(flīwāt′)n.
1.
a. A weight division in professional boxing having an upper limit of 112 pounds (50.4 kilograms), between junior flyweight and junior bantamweight.
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.
2. Something that is particularly small, light, or inconsequential.
flyweight′ adj.