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 research was part of a longitudinal study called Ten to Men by Australia’s Institute of Family Studies, which began in 2013 and now involves around 24,000 boys and men. —Lex Harvey, CNN Money, 5 June 2025

Buzz, ultimately freeing up space for a 53 x 83-in (135 x 210 cm) longitudinal bed extending out off the van's side. —New Atlas, 5 May 2025

In fact, a longitudinal study published in Psychological Science found that newlyweds who viewed their partner as closely resembling their ideal experienced little to no decline in marital satisfaction over three years. —Mark Travers, Forbes.com, 19 May 2025

Or even worse, a dangerous fantasy at a time when funding a longitudinal study on communal living could get your whole university canceled? —Hanna Rosin, The Atlantic, 19 May 2025

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