underweight

under- +‎ weight.

underweight (comparative more underweight, superlative most underweight)

1. Of an inappropriately or unusually low weight.

   He's so underweight he's had to buy smaller clothes.

   He's thirty pounds underweight.

   The market trader was fined for selling underweight bags of fruit.

2. Not too heavy for an intended purpose.

   The suitcase is just slightly underweight; I'll let it on the plane.

3. (finance) Being less invested in a particular area than market wisdom suggests.

   The fund is underweight in mining.

   • 2011, Murdoch, S. Foreigners back for Aussie stocks, The Australian

     "It's a long-run trend of foreign investors -- typically being underweight the banking sector in Australia," Mr Baker said.

• (of low weight): overweight
• (not too heavy): overweight

underweight (uncountable)

1. The state or quality of being underweight.
   • 1996, United States Institute of Medicine Committee on Scientific Evaluation of WIC Nutrition Risk Criteria, WIC Nutrition Risk Criteria: A Scientific Assessment, National Academies Press, →ISBN, page 110,

     Underweight reflects the body’s thinness, but the term does not necessarily imply the nature and causes of underweight.

• (state or quality): overweight

underweight (third-person singular simple present underweights, present participle underweighting, simple past and past participle underweighted)

1. (transitive) To underestimate the weight of.
2. (transitive) To give insufficient weight to (a consideration); to underestimate the importance of.