di·ur·nal
dī-ˈər-nᵊl 
1
a
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
2
a
: recurring every day
diurnal tasks
b
: having a daily cycle
diurnal tides
1
Synonyms
Examples of diurnal in a Sentence
Adjective
a love as constant and certain as the diurnal tides
Noun
a collection of diurnals containing essays by preeminent 19th-century American writers and thinkers
Recent Examples on the Web
Joseph V Micallef, Forbes, 11 Jan. 2025
The diurnal predator is believed to primarily consume trout and salmon, though it has also been observed eating puffins, crabs and deer carcasses.
—Brendan Rascius, Miami Herald, 2 Jan. 2025
The diurnal asymmetric warming of the earth has reversed course since 1991, with daytime temperatures rising faster than nighttime ones.
—Rafil Kroll-Zaidi, Harper's Magazine, 2 Apr. 2024
Izmir doesn’t have large diurnal shifts (the temperature difference between night and day) and without cooling periods, grapes can ripen faster and often lose acidity, which means those in Izmir are harvested almost 20 days earlier than the grapes in the inland Denizli province.
—Shana Clarke, Condé Nast Traveler, 22 May 2023
See all Example Sentences for diurnal 
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Adjective
This geographical feature funnels cool coastal winds into the Valley, creating a marked diurnal temperature variation.
—Joseph V Micallef, Forbes, 11 Jan. 2025
The diurnal predator is believed to primarily consume trout and salmon, though it has also been observed eating puffins, crabs and deer carcasses.
—Brendan Rascius, Miami Herald, 2 Jan. 2025
The diurnal asymmetric warming of the earth has reversed course since 1991, with daytime temperatures rising faster than nighttime ones.
—Rafil Kroll-Zaidi, Harper's Magazine, 2 Apr. 2024
Izmir doesn’t have large diurnal shifts (the temperature difference between night and day) and without cooling periods, grapes can ripen faster and often lose acidity, which means those in Izmir are harvested almost 20 days earlier than the grapes in the inland Denizli province.
—Shana Clarke, Condé Nast Traveler, 22 May 2023
See all Example Sentences for diurnal
Dictionary Entries Near diurnal
Cite this Entry
“Diurnal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diurnal. Accessed 21 Jan. 2025.
Copy CitationMedical Definition
diurnal
adjective
di·ur·nal
dī-ˈərn-ᵊl
1
: having a daily cycle
diurnal rhythms
2
a
: of, relating to, or occurring in the daytime
diurnal activity
b
: chiefly active during the daytime
diurnal mosquitoes
Love words? Need even more definitions?
Merriam-Webster unabridged
Share