underweight

Etymology

It is formed from English under- + weight,^{[2][3][4][5][6]} partly from the preposition under.^[2] The OED compares Danish undervægt, German Untergewicht and Dutch onderwigt.^[2]

Earliest recorded meaning

As a noun, insufficient weight: 1596 in Merriam-Webster and in the 1989 edition of the OED,^[4][7] 1629 in the current OED, in The Use of the Law.^[2]

Semantic evolution

The adjective appears much later: Merriam-Webster dates it to 1675,^[4] the Shorter Oxford to the late 17th century,^[3] while the OED and Etymonline give 1899, of a person lighter than average for their size.^[2][5] The noun followed this medical use, for an underweight person (1910) and the condition of being too light (1935).^[2] Merriam-Webster also records a commercial noun sense, the amount by which the shipping weight of lumber falls below the standard weight on which freight is charged.^[4] In finance, Collins records the adjective for having less invested in a market sector than the sector's size would suggest.^[8]

Timeline

• 1596 – noun, insufficient weight.^[4][7] The current OED's first record is from 1629.^[2]
• 1675 – adjective, weighing less than normal.^[4] The OED and Etymonline date the adjective to 1899.^[2][5]
• 1910 – noun, an underweight person.^[2]
• 1935 – noun, the condition of weighing too little for one's height and build.^[2]
• 1960 – adjective, figurative.^[2]

Meanings

Adjective

1. Weighing less than is normal, expected or healthy, especially for one's height and build: The vet said the puppy was underweight.^[8][4][2]
2. (finance) Holding a smaller share of a market sector than its size in the market would suggest; of a fund, invested in this way.^[8]

Noun

1. A lack of weight, or the amount by which something falls short of the required weight.^[4][2]
2. The condition of weighing less than is normal for one's age or height.^[4][2]
3. A person or thing that weighs less than normal.^[4][2]

Related words

• overweight
• weight

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
4. ^ a b c d e f g h i j Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
6. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
7. ^ a b Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
8. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins