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
Fluting and corrugation have also been added to the plate for longitudinal stiffness, and better traction comes via a Pwrtrac rubber outsole.
—
Ian Servantes, Footwear News, 5 Dec. 2025
Once across the Atlantic, Stubbs’ longitudinal skills failed him.
—Hamilton Cain, Boston Herald, 5 Dec. 2025
Meanwhile, to protect motorists from air pollution, Rogfast will use a longitudinal ventilation system powered by jet fans and supported by a vertical shaft extending to Kvitsøy.
—Georgina Jedikovska, Interesting Engineering, 3 Dec. 2025
In a longitudinal review of studies by the American Psychological Association, the emphasis is not only to cut down on screentime - which is linked to socioemotional problems in children - but also to improve the quality and social interactions through screentime.
—Mary Kekatos, ABC News, 1 Dec. 2025
See All Example Sentences for longitudinal
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Ian Servantes, Footwear News, 5 Dec. 2025
Once across the Atlantic, Stubbs’ longitudinal skills failed him.
—Hamilton Cain, Boston Herald, 5 Dec. 2025
Meanwhile, to protect motorists from air pollution, Rogfast will use a longitudinal ventilation system powered by jet fans and supported by a vertical shaft extending to Kvitsøy.
—Georgina Jedikovska, Interesting Engineering, 3 Dec. 2025
In a longitudinal review of studies by the American Psychological Association, the emphasis is not only to cut down on screentime - which is linked to socioemotional problems in children - but also to improve the quality and social interactions through screentime.
—Mary Kekatos, ABC News, 1 Dec. 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 8 Dec. 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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