un·​der·​weight | \ ˌən-dər-ˈwāt How to pronounce underweight (audio) \

Definition of underweight

 (Entry 1 of 2)

: weight below normal, average, or requisite weight



Definition of underweight (Entry 2 of 2)

: weighing less than the normal or requisite amount

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Synonyms & Antonyms for underweight

Synonyms: Adjective

Antonyms: Adjective

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Examples of underweight in a Sentence

Adjective the long illness left him frail and underweight
Recent Examples on the Web: Noun On Tuesday, Snapchat's lead underwriter Morgan Stanley downgraded Snap from equal weight to underweight and cut its price target to $16 from $28. Krishna Thakker, Fortune, "Here’s How Many Billions Evan Spiegel Has Lost Since Snap’s IPO," 12 July 2017 Recent Examples on the Web: Adjective Nelson said the animals were underweight and dehydrated, with several also having skin problems. Arkansas Online, "Arkansas woman, 38, arrested in animal cruelty case; more than 40 animals removed from 'deplorable' conditions, officials say," 24 Dec. 2019 BMI’s of under 25 were considered underweight or normal weight, 25 to 30 were considered overweight (25 to Beth Mole, Ars Technica, "Nearly 1 in 4 adults in the US will be severely obese by 2030, study suggests," 19 Dec. 2019 The wolf was underweight for its age, a mere 78 pounds compared with the usual 100- to 150-pound range, Matheson said. Leah Asmelash, CNN, "A family of four was on a camping trip in Canada. Then a wolf attacked while they were sleeping," 14 Aug. 2019 The dogs were found in poor living conditions, and police said several were very ill, malnourished, underweight or suffering from cancer. Nyssa Kruse, Arkansas Online, "12 dogs seized from unsanitary Jonesboro home," 27 Nov. 2019 Along with being underweight, the little cat also had a serious injury, one of his back legs was fractured in multiple places. Kelli Bender, PEOPLE.com, "One-Pound Kitten Who Lost a Leg After His Rescue, Gains a Family in Recovery," 22 Oct. 2019 As food became scarce, people became underweight, undernourished, and susceptible to disease. Jon Lee Anderson, The New Yorker, "In Its Fight with Venezuela, the Trump Administration Takes Aim at Cuba," 10 Oct. 2019 Half of the children were stunted, 17% were underweight, and a third screened positive for physical disability. Annabelle Timsit, Quartz Africa, "Rwanda’s radical plan to reduce poverty by harnessing fathers’ love," 8 Oct. 2019 Robeco, which has roughly $205 billion in assets under management, has been underweight on equities for about six weeks. Julia Horowitz, CNN, "Today in markets: Trade relief, and the lowest interest rates in 5,000 years," 5 Sep. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'underweight.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of underweight


1596, in the meaning defined above


1675, in the meaning defined above

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Time Traveler for underweight

Time Traveler

The first known use of underweight was in 1596

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Cite this Entry

“Underweight.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/underweight. Accessed 23 January 2020.

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More Definitions for underweight



English Language Learners Definition of underweight

: weighing less than the normal or expected amount : too light


un·​der·​weight | \ ˌən-dər-ˈwāt How to pronounce underweight (audio) \

Kids Definition of underweight

: weighing less than what is normal, average, or necessary


un·​der·​weight | \ -ˈwāt How to pronounce underweight (audio) \

Medical Definition of underweight

: 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

More from Merriam-Webster on underweight

Thesaurus: All synonyms and antonyms for underweight

Rhyming Dictionary: Words that rhyme with underweight

Comments on underweight

What made you want to look up underweight? Please tell us where you read or heard it (including the quote, if possible).


out of the ordinary or unreasonable

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