[ 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.

Origin of longitudinal

1535–45; < Latin longitūdin- (stem of longitūdō; see longitude) + -al1

OTHER WORDS FROM longitudinal

lon·gi·tu·di·nal·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for longitudinal

British Dictionary definitions for longitudinal

/ (ˌlɒndʒɪˈtjuːdɪnəl, ˌlɒŋɡ-) /


of or relating to longitude or length
placed or extended lengthwaysCompare transverse (def. 1)
psychol (of a study of behaviour) carried on over a protracted period of time

Derived forms of longitudinal

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

Medical definitions for longitudinal

[ lŏn′jĭ-tōōdn-əl ]


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.