From Longman Dictionary of Contemporary Englishfeatherweightfeath‧er‧weight /ˈfeðəweɪt $ -ər-/ noun [countable] DSOa boxer who weighs less than 57.15 kilograms, and who is heavier than a bantamweight but lighter than a lightweight
Examples from the Corpus
featherweight• Indeed, he was to train as a featherweight boxer during his year as a student at Battersea Polytechnic.• Darlington featherweight Jacob Smith signed a pro contract yesterday.• Rab thought of Winnie, her featherweight and money in the bank.• Just up two flights of stairs was quite enough, thank you - you're no featherweight.• You can only speculate at how Phoenix featherweight Louie Espinoza would have fared in the bout.• The problem seems to be that Cleese and co-writer Iain Johnstone have taken the featherweight demands of the romantic comedy to heart. 