: weighing less than the normal or requisite amount
Examples of underweight in a Sentence
Adjective
the long illness left him frail and underweight
Recent Examples on the Web
EW.com, 21 Aug. 2025
One area investors are underweight on is clean technology.
—Lee Ying Shan, CNBC, 13 Aug. 2025
The nurses down the hall don’t have neonatal incubators, which are the standard treatment for underweight babies born in the rich places of the world.
—Literary Hub, 8 Aug. 2025
Child stunting and food insecurity levels fell, while adult obesity went up: Since 2016, there have been more obese people worldwide than underweight ones.
—Tom Chivers, semafor.com, 4 Aug. 2025
See All Example Sentences for underweight
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Adjective
Per the National Institutes of Health's standards, this is considered underweight.
—EW.com, 21 Aug. 2025
One area investors are underweight on is clean technology.
—Lee Ying Shan, CNBC, 13 Aug. 2025
The nurses down the hall don’t have neonatal incubators, which are the standard treatment for underweight babies born in the rich places of the world.
—Literary Hub, 8 Aug. 2025
Child stunting and food insecurity levels fell, while adult obesity went up: Since 2016, there have been more obese people worldwide than underweight ones.
—Tom Chivers, semafor.com, 4 Aug. 2025
See All Example Sentences for underweight
Cite this Entry
“Underweight.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/underweight. Accessed 9 Sep. 2025.
Copy CitationMedical Definition
underweight
adjective
un·der·weight
-ˈwāt 
: weighing less than the normal amount for one's age, height, and build
underweight children
underweight adults typically have a body mass index of less than 18.5
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