Definition of "Lightweight" :
noun: a professional boxer who weighs between 131 and 135 pounds
noun: a wrestler who weighs 139-154 pounds
noun: an amateur boxer who weighs no more than 132 pounds
noun: someone who is unimportant but cheeky and presumptuous
adjective: weighing relatively little compared with another item or object of similar use
"A lightweight fabric."
adjective: having no importance or influence
"A lightweight intellect."