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
Usually, though, it would be complemented by a transverse rear bed, because a longitudinal bed layout simply wouldn't fit behind the popular tandem bathroom compartment and front dinette.
—
New Atlas, 9 Sep. 2025
For students, a longitudinal study found that those from food-insecure households were 43% less likely to graduate from college.
—Casey Castillo, San Diego Union-Tribune, 9 Sep. 2025
Over the past nine years, Intuition Robotics has conducted a longitudinal study to explore how AI can provide health and wellness support to older adults.
—Gil Press, Forbes.com, 8 Sep. 2025
Likewise, as articulated by the American Public Health Association in a 2018 policy brief and a 2025 longitudinal study, research shows that excessive investment in policing — at the expense of social services — is correlated with higher suicide mortality and diminished community well-being.
—Hansel Alejandro Aguilar, Mercury News, 6 Sep. 2025
See All Example Sentences for longitudinal
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New Atlas, 9 Sep. 2025
For students, a longitudinal study found that those from food-insecure households were 43% less likely to graduate from college.
—Casey Castillo, San Diego Union-Tribune, 9 Sep. 2025
Over the past nine years, Intuition Robotics has conducted a longitudinal study to explore how AI can provide health and wellness support to older adults.
—Gil Press, Forbes.com, 8 Sep. 2025
Likewise, as articulated by the American Public Health Association in a 2018 policy brief and a 2025 longitudinal study, research shows that excessive investment in policing — at the expense of social services — is correlated with higher suicide mortality and diminished community well-being.
—Hansel Alejandro Aguilar, Mercury News, 6 Sep. 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 18 Sep. 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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