Definition of longitudinal
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
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Merriam-Webster unabridged
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Time Traveler for longitudinal
The first known use of longitudinal was in the 15th century
See more words from the same century