The word lightweight usually refers to a class of athletes in a particular sport, based on their weight. It is also a slang term, indicating insignifigance or ineptitude.
The lightweight is the 130 pounds (59 kilograms) to 135 pounds (61 kilograms) weight class in the sport of boxing. In England, it equates to the weight bracket of 9 st 3 lb - 9 st 8 lb.
Notable lightweight boxers includes Bummy Davis, Benny Leonard, Henry Armstrong, Joe Gans, Tony Canzoneri, Carlos Ortiz, Ike Williams,Roberto Duran, Alexis Arguello, Ray "Boom Boom" Mancini, Hector "Macho" Camacho, Julio César Chávez, Miguel Angel Gonzalez, Oscar De La Hoya, Sugar Shane Mosley, Colin Smith, Floyd Mayweather Jr., Diego Corrales, and the current Ring Magazine champion, Joel Casamayor.