lightweight

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. One that weighs relatively little or less than average.
2. n. A weight division in professional boxing having an upper limit of 135 pounds (60.7 kilograms), between junior lightweight and junior welterweight.
3. n. A boxer competing in this weight division.
4. n. A similar weight division in other sports, such as weightlifting.
5. n. A contestant in this weight division.
6. n. A person of little ability, intelligence, influence, or importance.
7. adj. Weighing relatively little; not heavy: lightweight clothing; a lightweight wood.
8. adj. Sports Of, relating to, or characteristic of a lightweight: the lightweight title.
9. adj. Having no significance or influence: a lightweight intellect.

Century Dictionary and Cyclopedia

1. n. In sporting, a man or an animal of a certain weight prescribed by the rules, between that of the middle-weight on one hand and that of the feather-weight on the other; hence, any person of light weight or of comparatively little importance.

Wiktionary

1. n. boxing A boxer in a weight division having a maximum limit of 135 pounds for professionals and 132 pounds for amateurs.
2. n. bodybuilding A competitive weight division between bantamweight and welterweight, with specific weights varying by organization.
3. n. One of little consequence or ability.
4. n. A person who can't handle their drink.
5. n. A political candidate with little chance of winning
6. adj. Lacking in earnestness, ability, or profundity
7. adj. Having less than average weight
8. adj. Lacking in strength

GNU Webster's 1913

1. adj. [Cant] a prize fighter, boxer, wrestler, or jockey, who is below a standard medium weight. Cf. Feather weight, under Feather.
2. n. One of less than average weight In boxing, wrestling, etc., one weighing not more than 133 pounds (U. S. amateur rules 135 pounds, Eng. 140 pounds).
3. n. Colloq., Chiefly U. S., Colloq., Chiefly U. S. A person of small importance or mental ability, especially one who is unimportant but cheeky and presumptuous.
4. n. a wrestler who weighs 139-154 pounds.
5. adj. Light in weight, as a coin; specif., applied to a man or animal who is a lightweight.
6. adj. made of thin cloth, of relatively little weight; -- of clothing or fabrics.

WordNet 3.0

1. n. someone who is unimportant but cheeky and presumptuous
2. n. an amateur boxer who weighs no more than 132 pounds
3. adj. weighing relatively little compared with another item or object of similar use
4. n. a wrestler who weighs 139-154 pounds
5. n. a professional boxer who weighs between 131 and 135 pounds
6. adj. having no importance or influence