heavy·weight 
/ˈhɛviˌweɪt/ noun
plural heavy·weights /ˈhɛviˌweɪt/ noun [count] 1 : a fighter in the heaviest class of boxers : a boxer who weighs more than 175 pounds (79.5 kilograms) — often used before another noun ▪ They are fighting for the heavyweight title. ▪ the heavyweight champion of the world 2 : someone or something that is very important and powerful
▪ Their company is one of the industry's heavyweights. 3 : something that is heavy — often used before another noun ▪ heavyweight paper ▪ heavyweight cotton/wool/silk
▪ Their company is one of the industry's heavyweights.
