Pronunciation: (līt'wāt"),[key] —adj. 1. light in weight.
2. being lighter in weight, texture, etc., than another item or object of identical use, quality, or function: a lightweight topcoat; a lightweight alloy for ship construction. 3. without seriousness of purpose; trivial or trifling: lightweight reading. 4. of or pertaining to a lightweight: He's the new lightweight contender. 5. (of a horse, esp. a hunter) able to carry up to 165 lb. (75 kg).
—n. 1. a person of less than average weight.
2. Informal.a person who is of little influence, importance, or effect.
3. a boxer or other contestant intermediate in weight between a featherweight and a welterweight, esp. a professional boxer weighing between 126 and 135 lb. (56.7–61 kg).