lightweightnoun/ˈlaɪt.weɪt/

• 1

  A particular weight class, or member of such, as prescribed by the rules, between that of the heavier welterweight and the lighter featherweight. See Wikipedia for the specifics of each sport.

• 2

  hobbieslifestylerowingA particular weight category as prescribed by the rules, separate from an open or heavyweight class.

• 3

  hobbieslifestylesportsA competitive weight division as prescribed by the rules, between the heavier middleweight and the lighter featherweight.

• 4

  One of little consequence or ability.

• 5

  A person who cannot handle their drink; one who gets drunk on very little alcohol.

  • "Wait, is this about the other night when you two lightweights totally went on that bender?"
• 6

  A person with low endurance.

• 7

  A political candidate with little chance of winning.

• 8

  Something that is light in weight, or relatively so.

  • He mentions the "huge engine, lying on its side"—it was in fact a 2-2-2 weighing but 27 tons, something of a lightweight, even for 1868.

lightweightadj/laɪtˈweɪt/

• 1

  Lacking in earnestness, ability, or profundity.

• 2

  Having less than average weight.

  • […] the Plan incorporates in proper combination every available modern technique, including extensive electrification on the new standard high-voltage a.c. system at a frequency of 50 cycles; main-line diesel traction as a half-way house to electrification; lightweight diesel trains for secondary and branch services; and a smaller wagon fleet doing more work by the use of continuous brakes in conjunction with modernised terminals and marshalling yards.
  • For example, lightweight construction and Jacobs bogies save weight, and a lighter train uses less power.
• 3

  Lacking in strength.

  • With the Gunners far too lightweight in midfield, Mikel Arteta dropped back into a deeper-lying role. This freed Yossi Benayoun to go further forward, a move that helped forge a rare Arsenal chance on 30 minutes when the Israeli released Van Persie, only for the Dutchman's snap-shot to be tipped around the post.
• 4

  computingengineeringmathematicsHaving a small footprint or performance impact.

lightweightverb

• 1

  To reduce the amount or weight of.

  • By extending the producer’s responsibility to the product’s disposal (its post-consumer life), issues previously outside the business calculus become of paramount importance. Because a producer knows it will have to bear the cost of collecting and valorizing the product, it must manage a new set of business matters. Can the packaging be lightweighted? Are the materials all recyclable?
  • The solar photovoltaic array, GPS antennae and telephony antenna all would be lightweighted and integrated into the balloon structure, and the sensor-module would be ruggedized and miniaturized.