longitudinal
adjective
lon·gi·tu·di·nal
ˌlän-jə-ˈtüd-nəl 
-ˈtyüd-,
-ˈt(y)ü-dᵊn-əl,
British also ˌläŋ-gə-
1
: placed or running lengthwise
The insect's back is black with yellow longitudinal stripes.
2
: of or relating to length or the lengthwise dimension
the longitudinal extent of the building
3
: involving the repeated observation or examination of a set of subjects over time with respect to one or more study variables
a longitudinal study of juvenile offenders over a period of five years
longitudinally
adverb
Examples of longitudinal in a Sentence
The insect's body is black with yellow longitudinal stripes.
calculating the longitudinal position of a ship
a longitudinal study of career aspirations among girls from 5 to 17
Recent Examples on the Web
In fact, a longitudinal study published in Psychological Science found that newlyweds who viewed their partner as closely resembling their ideal experienced little to no decline in marital satisfaction over three years.
—
Mark Travers, Forbes.com, 19 May 2025
Or even worse, a dangerous fantasy at a time when funding a longitudinal study on communal living could get your whole university canceled?
—Hanna Rosin, The Atlantic, 19 May 2025
Parenting in childhood predicts personality in early adulthood: A longitudinal twin-differences study.
—Daniella Gray, MSNBC Newsweek, 11 May 2025
With this longitudinal study, however, researchers could separate those who went on to have a T.I.A. from a group that went on to suffer a stroke and also from an asymptomatic control group.
—Paula Span, New York Times, 17 May 2025
See All Example Sentences for longitudinal
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Mark Travers, Forbes.com, 19 May 2025
Or even worse, a dangerous fantasy at a time when funding a longitudinal study on communal living could get your whole university canceled?
—Hanna Rosin, The Atlantic, 19 May 2025
Parenting in childhood predicts personality in early adulthood: A longitudinal twin-differences study.
—Daniella Gray, MSNBC Newsweek, 11 May 2025
With this longitudinal study, however, researchers could separate those who went on to have a T.I.A. from a group that went on to suffer a stroke and also from an asymptomatic control group.
—Paula Span, New York Times, 17 May 2025
See All Example Sentences for longitudinal
Cite this Entry
“Longitudinal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/longitudinal. Accessed 2 Jun. 2025.
Copy CitationKids Definition
longitudinal
adjective
lon·gi·tu·di·nal
ˌlän-jə-ˈt(y)üd-nəl
-ᵊn-əl
1
: of or relating to length
2
: placed or running lengthwise
longitudinally
adverb
-ē
Medical Definition
longitudinal
adjective
lon·gi·tu·di·nal
ˌlän-jə-ˈt(y)üd-ᵊn-əl, -nəl, British also ˌläŋ-gə-ˈtyüd-
1
: of, relating to, or occurring in the lengthwise dimension
a longitudinal bone fracture
2
: extending along or relating to the anteroposterior axis of a body or part
a trypanosome which reproduces by longitudinal fission
3
: involving the repeated observation or examination of a set of subjects over time with respect to one or more study variables (as general health, the state of a disease, or mortality)
a longitudinal study of heart transplant recipients over a five-year period
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