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

The longitudinal strips of the rose petals did indeed curl up, suggesting that the petal preferentially curves in this direction. — Manon Bischoff, Scientific American, 13 Oct. 2026

Indiana has served as CARE’s administrative operations core, while Michigan has led the group’s longitudinal clinical study, which involves dozens of other universities. — Daniel Libit, Sportico.com, 12 Oct. 2026

Haroz and many other experts believe benchmarks can only get us so far, and that researchers need longitudinal data from AI companies to connect exposure to actual outcomes in real people. — Laura Reiley, Vanity Fair, 9 Oct. 2026

Yet according to solid longitudinal polling, the degree to which Americans prioritized terrorism no longer reflected quotidian reality. — Daniel Benjamin, Foreign Affairs, 11 Sep. 2026

Word History

First Known Use

15th century, in the meaning defined at sense 2

Phrases Containing longitudinal

• longitudinal wave

Rhymes for longitudinal

• altitudinal
• attitudinal
• latitudinal

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