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[lon-ji-tood-n-l, -tyood-] /ˌlɒn dʒɪˈtud n l, -ˈtyud-/
of or relating to longitude or length:
longitudinal measurement.
extending in the direction of the length of a thing; running lengthwise:
a thin, longitudinal stripe.
Zoology. pertaining to or extending along the long axis of the body, or the direction from front to back, or head to tail.
pertaining to a research design or survey in which the same subjects are observed repeatedly over a period of time.
a longitudinal framing member, as in the hull of a ship.
1535-45; < Latin longitūdin- (stem of longitūdō; see longitude) + -al1
Related forms
longitudinally, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for longitudinal
  • Social scientists who study relational aggression point to a dearth of longitudinal data.
  • It's the first-ever longitudinal study of the little-understood problem.
  • The lack of longitudinal rigidity led directly to the collapse.
  • We need longitudinal studies looking at infidelity over the course of people's married lives.
  • Preliminary experiments have been conducted with the generation of a longitudinal gravity wave in the quantised space-time.
  • The rear wheels, in addition to longitudinal height adjustment, would have lateral adjustment as well.
  • longitudinal data indicate that students who study more in college earn more in the long run.
  • Sound waves are longitudinal with the displacements in the same direction as the wave.
  • For the first time it was possible to test the optimistic view against a large and longitudinal body of evidence.
  • Possibly longitudinal observation would be better, but the decisions may be weaker than in a series of specific experiments.
British Dictionary definitions for longitudinal


/ˌlɒndʒɪˈtjuːdɪnəl; ˌlɒŋɡ-/
of or relating to longitude or length
placed or extended lengthways Compare transverse (sense 1)
(psychol) (of a study of behaviour) carried on over a protracted period of time
Derived Forms
longitudinally, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for longitudinal

1706, from Latin longitudo (see longitude) + -al (1).

Online Etymology Dictionary, © 2010 Douglas Harper
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longitudinal in Medicine

longitudinal lon·gi·tu·di·nal (lŏn'jĭ-tōōd'n-əl, -tyōōd'-)
Running in the direction of the long axis of the body or any of its parts.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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