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[dahy-ur-nl] /daɪˈɜr nl/
of or relating to a day or each day; daily.
of or belonging to the daytime (opposed to nocturnal).
Botany. showing a periodic alteration of condition with day and night, as certain flowers that open by day and close by night.
active by day, as certain birds and insects (opposed to nocturnal).
Liturgy. a service book containing offices for the daily hours of prayer.
Archaic. a diary.
Archaic. a newspaper, especially a daily one.
Origin of diurnal
late Middle English
1400-50; late Middle English < Latin diurnālis, equivalent to diurn(us) daily + -ālis -al1
Related forms
diurnally, adverb
diurnalness, noun
transdiurnal, adjective
undiurnal, adjective
undiurnally, adverb
Can be confused
diurnal, nocturnal. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for diurnally
Historical Examples
  • Mountain and valley breezes furnish another example of diurnally reversed winds.

    Meteorology Charles Fitzhugh Talman
  • I think we should diurnally station a good London band on high, and play his Majesty to bed—the sun.

    Evan Harrington, Complete George Meredith
  • It had never before dawned upon us that we thus added three uncounted miles to our fourteen diurnally counted ones.

British Dictionary definitions for diurnally


happening during the day or daily
(of flowers) open during the day and closed at night
(of animals) active during the day Compare nocturnal
a service book containing all the canonical hours except matins
Derived Forms
diurnally, adverb
Word Origin
C15: from Late Latin diurnālis, from Latin diurnus, from diēs day
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 diurnally



late 14c., from Late Latin diurnalis "daily," from Latin dies "day" + -urnus, an adjectival suffix denoting time (cf. hibernus "wintery"). Dies "day" is from PIE root *dyeu- "to shine" (cf. Sanskrit diva "by day," Welsh diw, Breton deiz "day;" Armenian tiw; Lithuanian diena; Old Church Slavonic dini, Polish dzień, Russian den), literally "to shine" (cf. Greek delos "clear;" Latin deus, Sanskrit deva "god," literally "shining one;" Avestan dava- "spirit, demon;" Lithuanian devas, Old Norse tivar "gods;" Old English Tig, genitive Tiwes, see Tuesday).

Online Etymology Dictionary, © 2010 Douglas Harper
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diurnally in Medicine

diurnal di·ur·nal (dī-ûr'nəl)

  1. Having a 24-hour period or cycle; daily.

  2. Occurring or active during the daytime rather than at night.

di·ur'nal·ly adv.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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diurnally in Science
    1. Occurring once in a 24-hour period; daily.

    2. Having a 24-hour cycle. The movement of stars and other celestial objects across the sky are diurnal.

  1. Most active during the daytime. Many animals, including the apes, are diurnal.

  2. Having leaves or flowers that open in daylight and close at night. The morning glory and crocus are diurnal. Compare nocturnal.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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