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

Research has confirmed the safety of vaccine ingredients, including thimerosal, which was once a concern for its mercury content, and longitudinal studies have demonstrated that on-time vaccination in the first year of life does not adversely affect neuropsychological outcomes later in childhood. —A.j. Russo, Baltimore Sun, 3 Dec. 2024

This includes continuous streams of data generated over extended periods and longitudinal care involving multiple modalities (therapy, medication, lifestyle interventions) that require integration for comprehensive care. —Surabhi Bhandari, Forbes, 3 Dec. 2024

Belly and body fat boosts risk The study, published Tuesday in the Journal of Neurology, Neurosurgery & Psychiatry, looked at data on more than 34,000 men and women ages 45 to 82 who provided abdominal and brain scans to the UK Biobank, a longitudinal health study based in the UK. —Sandee Lamotte, CNN, 26 Nov. 2024

However, these lines could also result from nail psoriasis or longitudinal melanonychia (effectively a mole of the nail), Stringer says. —Caroline C. Boyle, USA TODAY, 12 Nov. 2024

Word History

First Known Use

15th century, in the meaning defined at sense 2

Phrases Containing longitudinal

• longitudinal wave

Kids 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

-ē

adverb

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

longitudinally

-ē 

adverb