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
Vertical seismic forces are transferred directly to the foundation via pier supports and cable stays, while longitudinal and lateral horizontal forces are absorbed and dissipated using specialized hydraulic dampers, friction pendulum bearings, and synthetic rubber pads.
—
New Atlas, 27 May 2026
This finding held up across a long-term longitudinal follow-up, too.
—Mark Travers, Forbes.com, 26 May 2026
Much of the existing research is observational, with relatively small sample sizes, few longitudinal studies and only limited data on elite athletes or sport-specific outcomes.
—Starre Vartan, CNN Money, 20 May 2026
The resulting longitudinal pre-tensioning of the whole structure compressed the joints.
—Srishti Gupta, Interesting Engineering, 16 May 2026
See All Example Sentences for longitudinal
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New Atlas, 27 May 2026
This finding held up across a long-term longitudinal follow-up, too.
—Mark Travers, Forbes.com, 26 May 2026
Much of the existing research is observational, with relatively small sample sizes, few longitudinal studies and only limited data on elite athletes or sport-specific outcomes.
—Starre Vartan, CNN Money, 20 May 2026
The resulting longitudinal pre-tensioning of the whole structure compressed the joints.
—Srishti Gupta, Interesting Engineering, 16 May 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 29 May. 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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