Diurnal
adjective /daɪˈɜː.nəl/ — Active during the day; relating to the daytime.
Definition
Active during the day, as opposed to nocturnal. Also describes processes or events that occur during the day or repeat daily. Most humans and many birds are diurnal; bats, owls, and many insects are nocturnal.
Beyond the definition
To be diurnal is to be organized by light — to have evolved around the cycle of day. There's something reassuring about that: the body tuned to the oldest clock.
Origin & history
From Latin 'diurnalis' (daily); from 'dies' (day). Related to 'journal' (daily record) and 'journey' (one day's travel).
Example sentences
Illustrative sentences for learning, not verified community posts or sourced quotations.
Most birds of prey are diurnal — hunting by sight requires light, and light is the day's gift.
Her insomnia had made her inadvertently nocturnal; she was trying to reset to diurnal before the job started.
The markets open and close on a diurnal rhythm — money organized by the same cycle as flowers.
How to use it
This entry uses an adjective. Follow the examples for the nouns it describes and its position in the sentence.
Choose “Diurnal” when the meaning fits your context: Active during the day, as opposed to nocturnal. Also describes processes or events that occur during the day or repeat daily. Most humans and many birds are diurnal; bats, owls, and many insects are nocturnal.
Synonyms
daytime, day-active
Antonyms
nocturnal, night-active
Related words
Diurnal vs nocturnal
Diurnal refers to creatures or processes that are active during the day, whereas nocturnal describes those active at night. Use diurnal when discussing sun-cycle patterns and nocturnal for nighttime behaviors.
Word in the Wild
See how this word appears in life, language and stories.
Illustrative sentences and imagined stories for learning — not verified sightings, interviews, or sourced quotations.
Fictional scene
Busy day in local cafe
An adult chats with a friend in a warm, bright, local café, with natural light filling the space.
The activity and natural light in the café during the day illustrate the diurnal cycle, where the environment is active and bustling under the sunlight.
Image credit: Wordspun · AI-generated conceptual illustration
Questions about this word
What does "Diurnal" mean?
Diurnal is adjective meaning: Active during the day; relating to the daytime.. Active during the day, as opposed to nocturnal. Also describes processes or events that occur during the day or repeat daily. Most humans and many birds are diurnal; bats, owls, and many insects are nocturnal.
Where does the word "Diurnal" come from?
From Latin 'diurnalis' (daily); from 'dies' (day). Related to 'journal' (daily record) and 'journey' (one day's travel).