WordNet
light middleweight
n. an amateur boxer who weighs no more than 156 pounds
Wikipedia
Light middleweight
Light middleweight, also known as junior middleweight or super welterweight, is a weight class in combat sports.
Usage examples of "light middleweight".
Charlie, now a light middleweight, couldn't wait to get in the ring while Tommy somehow managed to keep himself out of the firing line, although both of them became aware of Captain Trentham's menacing presence as his swagger stick continually struck the side of his leg.