longitudinal
Americanadjective
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of or relating to longitude or length.
longitudinal measurement.
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extending in the direction of the length of a thing; running lengthwise.
a thin, longitudinal stripe.
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Zoology. pertaining to or extending along the long axis of the body, or the direction from front to back, or head to tail.
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pertaining to a research design or survey in which the same subjects are observed repeatedly over a period of time.
noun
adjective
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of or relating to longitude or length
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placed or extended lengthways Compare transverse
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psychol (of a study of behaviour) carried on over a protracted period of time
Other Word Forms
Derived Forms
Etymology
Origin of longitudinal
1535–45; < Latin longitūdin- (stem of longitūdō; see longitude) + -al 1
Explanation
Use the adjective longitudinal to describe something that takes place over a long period of time, like a study of the lifetime eating habits of people who live on islands. Sociologists and other scientists use the word longitudinal when they're talking about long-term research. Geographers also describe things as longitudinal, but instead they mean something that relates to the east-west measurement across the Earth. When doctors use the word, it's in yet another way, describing muscles or other body parts that run lengthwise, rather than up-and-down. Longitudinal comes from the Latin word longitudo, "length or duration."
Vocabulary lists containing longitudinal
The Old Man and the Sea
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This Week in Words: Current Events Vocab for February 3–February 9, 2024
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Articles on Benefits of Technology
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
A 2026 longitudinal study in the Journal of Public Health reached a similar conclusion.
From The Wall Street Journal • Mar. 27, 2026
Then, I used the longitudinal feature of the CPS to follow up with those same individuals when they were interviewed one year later.
From MarketWatch • Dec. 18, 2025
A recent cover article in Aging-US, titled "Sex-specific longitudinal reversal of aging in old frail mice," highlights a promising new direction in longevity research.
From Science Daily • Dec. 2, 2025
Marc was accepted into AllFTD, a longitudinal study that is the largest ever conducted for this disease.
From Los Angeles Times • Sep. 7, 2025
You can view here animations of longitudinal and transverse waves, single particles being disturbed by a transverse wave or by a longitudinal wave, and particles being disturbed by transverse and longitudinal waves.
From "Understanding Basic Music Theory" by Catherine Schmidt-Jones and Russel Jones
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
