[adjective uhn-der-weyt; noun uhn-der-weyt]


weighing less than is usual, required, or proper.


deficiency in weight below a standard or requirement.

Origin of underweight

First recorded in 1590–1600; under- + weight
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for underweight

Contemporary Examples of underweight

Historical Examples of underweight

  • They could as easily have charged you overweight as underweight.

    Uncle Sam Detective

    William Atherton Du Puy

  • The baby of a German housewife was underweight—that is, below normal.

    A Stake in the Land

    Peter Alexander Speek

  • They are the people who are overweight and the people who are underweight.


    James J. Walsh

  • Blind abscesses at the roots will cause all sorts of aches and pains, as well as underweight.

    Diet and Health

    Lulu Hunt Peters

  • Underweight individuals sometimes have to train their digestive tracts for some of the foods they need.

    Diet and Health

    Lulu Hunt Peters

British Dictionary definitions for underweight



weighing less than is average, expected, or healthy
  1. having a lower proportion of one's investments in a particular sector of the market than the size of that sector relative to the total market would suggest
  2. (of a fund etc) disproportionately invested in this waypension funds have become underweight of equities
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for underweight

1899, from under- + weight.

Online Etymology Dictionary, © 2010 Douglas Harper

underweight in Medicine




Weighing less than is normal, healthy, or required.


Insufficiency of weight.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.