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
This may help explain why healthcare spending in the United States remains so concentrated around acute intervention rather than longitudinal disease prevention.
—
Jeffrey Wessler, Forbes.com, 18 June 2026
Queen says more experiments are needed, including looking at more long-term longitudinal data and identifying causal relationships in animal models with specific bacterial strains.
—Joseph Kim, NPR, 16 June 2026
The experiment was run many times in several variations, and Mischel and others returned to it in longitudinal studies to see how the children who had held out for two marshmallows at age 3 fared at age 13 or 30.
—Ian Bogost, The Atlantic, 16 June 2026
For example, using geometry and the longitudinal position of the home, the team angled the awning over the windows in the main living space so shade falls in front of the house in summer and moves deep into the living area in winter to heat the polished concrete floor.
—Noah Daly, Idaho Statesman, 13 June 2026
See All Example Sentences for longitudinal
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Jeffrey Wessler, Forbes.com, 18 June 2026
Queen says more experiments are needed, including looking at more long-term longitudinal data and identifying causal relationships in animal models with specific bacterial strains.
—Joseph Kim, NPR, 16 June 2026
The experiment was run many times in several variations, and Mischel and others returned to it in longitudinal studies to see how the children who had held out for two marshmallows at age 3 fared at age 13 or 30.
—Ian Bogost, The Atlantic, 16 June 2026
For example, using geometry and the longitudinal position of the home, the team angled the awning over the windows in the main living space so shade falls in front of the house in summer and moves deep into the living area in winter to heat the polished concrete floor.
—Noah Daly, Idaho Statesman, 13 June 2026
See All Example Sentences for longitudinal
Cite this Entry
“Longitudinal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/longitudinal. Accessed 19 Jun. 2026.
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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