di·​ur·​nal | \ dī-ˈər-nᵊl How to pronounce diurnal (audio) \

Definition of diurnal

 (Entry 1 of 2)

1a biology : active chiefly in the daytime diurnal animals
b : of, relating to, or occurring in the daytime the city's diurnal noises
c botany : opening during the day and closing at night diurnal flowers
2a : recurring every day diurnal tasks
b : having a daily cycle diurnal tides



Definition of diurnal (Entry 2 of 2)

2 archaic : diary, daybook

Other Words from diurnal


diurnally \ dī-​ˈər-​nᵊl-​ē How to pronounce diurnal (audio) \ adverb

Examples of diurnal in a Sentence

Adjective a love as constant and certain as the diurnal tides Noun a microfilm containing a collection of diurnals published by 19th-century American abolitionists
Recent Examples on the Web: Adjective The trailer opens with clips of Alice (Pugh) and Jack (Styles) approaching their new life with optimism, happy with the diurnal chores and picture-perfect lifestyle provided by Jack’s experimental company town housing, Victory Project. Tomás Mier, Rolling Stone, 21 July 2022 This diurnal temperature shift allows excellent concentration of sugars while at the same time maintaining acidity . Mike Desimone And Jeff Jenssen, Forbes, 11 July 2022 For instance, ungulates, such as bison, and coyotes are generally crepuscular, or most active at dusk and dawn, whereas alligators are diurnal and nocturnal. Andrea Sachs, Washington Post, 22 June 2022 Given the diurnal minimum of heating early in the day, any storms will struggle against that. Ian Livingston, Washington Post, 15 June 2022 Numerous diverse mesoclimates and soils give vineyards distinct personalities, but in general, summers are warm and dry, with cool evenings and a diurnal temperature range that helps preserve acidity and freshness in the grapes. Lana Bortolot, Forbes, 27 May 2022 Scientists saw that the eye size and shape were similar to those of modern diurnal owls. Margaret Osborne, Smithsonian Magazine, 4 Apr. 2022 In the Dundee study, researchers found that this diurnal decrease is absent, or at least relatively absent, in a deprived population who do not have regular access to and use of green spaces in their urban environment. Shane O'mara, Outside Online, 13 May 2020 But a few owls are diurnal—or active during the day. Margaret Osborne, Smithsonian Magazine, 4 Apr. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'diurnal.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of diurnal


14th century, in the meaning defined at sense 2a


1600, in the meaning defined at sense 2

History and Etymology for diurnal


Middle English, from Latin diurnalis — more at journal


derivative of diurnal entry 1

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The first known use of diurnal was in the 14th century

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diurnal arc

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Last Updated

25 Jul 2022

Cite this Entry

“Diurnal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diurnal. Accessed 17 Aug. 2022.

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More Definitions for diurnal


di·​ur·​nal | \ dī-ˈərn-ᵊl How to pronounce diurnal (audio) \

Medical Definition of diurnal

1 : having a daily cycle diurnal rhythms
2a : of, relating to, or occurring in the daytime diurnal activity
b : chiefly active during the daytime diurnal mosquitoes

Other Words from diurnal

diurnally \ -​ᵊl-​ē How to pronounce diurnal (audio) \ adverb

More from Merriam-Webster on diurnal

Nglish: Translation of diurnal for Spanish Speakers

Britannica English: Translation of diurnal for Arabic Speakers


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