featherweight

noun3

1. •
   A weight class in many combat sports; e.g. in professional boxing of a maximum of 126 pounds or 57.2 kilograms.
2. •
   A sportsman who fights in this division.

   • Watson specializes in adiposeness; none of his chorus beauties may be considered featherweights. — 1923
3. •
   The lightest weight that may be carried by a racehorse.