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

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Other Words from diurnal


diurnally \ dī-​ˈər-​nᵊl-​ē How to pronounce diurnally (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 first is the basic diurnal nature of renewable generation—solar doesn’t generate at night, after all, and wind generation is often low midday. Nathaniel Bullard, Bloomberg.com, "It’s Always Sunny in India’s Renewable Power Market," 8 June 2020 Our song bird species are diurnal (daytime) feeders and eat insects that are active during the day. oregonlive, "Does welcoming bats to yard reduce food for wild birds? Ask an expert," 6 June 2020 This diurnal pattern is also seen on Mars—something scientists weren’t expecting to detect from the surface. National Geographic, "Mars is humming. Scientists aren’t sure why.," 24 Feb. 2020 Under the new law, which takes effect in 90 days, pet dealers are required to regularly groom animals to prevent matting and flea and tick infestations and provide animals with diurnal lighting cycles, which mimic natural, 24-hour light patterns. USA TODAY, "Smokey Bear, tarantula trek, censoring Adam and Eve: News from around our 50 states," 9 Aug. 2019 Passive house systems work really well in climates with big diurnal temperature swings, like the desert. New York Times, "Do Americans Need Air-Conditioning?," 3 July 2019 That diurnal cycle is linked to the giant impact by a fundamental law of physics, the conservation of angular momentum. Simon J. Lock, Scientific American, "When Earth and the Moon Were One," 2 July 2019 These sorts of scenes seem to create a theater set across which Tillim’s subjects move, like characters enacting a diurnal purpose. Carole Naggar, The New York Review of Books, "Framing Time: Guy Tillim’s African Street Photography," 25 May 2019 By analyzing coyote scat, scientists have linked this behavioral change to dietary shifts from diurnal to nocturnal prey, with implications for small mammal communities and for competition with other predators. Kaitlyn Gaynor, CNN, "To avoid humans, more wildlife now work the night shift," 14 June 2018

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.

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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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Time Traveler for diurnal

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

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Cite this Entry

“Diurnal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diurnal. Accessed 28 Oct. 2020.

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More Definitions for diurnal


How to pronounce diurnal (audio)

English Language Learners Definition of diurnal

: active mainly during the day
: happening every day


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 diurnally (audio) \ adverb

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