Definition of diurnal in English:


Syllabification: di·ur·nal
Pronunciation: /dīˈərnl


  • 1Of or during the day.
    More example sentences
    • When I was first married I was practically nocturnal, and my wife was diurnal.
    • It's now 6am, which is the equivalent of 6pm for all of those conservative diurnal types.
    • I'll get maybe three, four good diurnal emissions off per day, I reckon.
  • 1.1 Zoology (Of animals) active in the daytime.
    More example sentences
    • They are diurnal herbivores, hiding in reef crevices during nighttime and browsing over reefs to feed during the day.
    • Conversely, subdominant fish were diurnal and occupied large home ranges by day but were generally not observed at night.
    • Accipitrids are diurnal birds of prey with broad wings, hooked beaks, strong legs and feet and sharp talons.
  • 1.2 Botany (Of flowers) open only during the day.
    More example sentences
    • Are diurnal changes of turgor and leaf growth correlated with each other?
    • Ammonium concentrations in roots and leaves undergo diurnal changes.
    • NRA showed important diurnal changes in leaves and roots tissues.
  • 2Daily; of each day: diurnal rhythms
    More example sentences
    • Universal, reliable and even human-made light, completely independent of diurnal rhythm, has abolished the shamanist aspects of our calling.
    • This apparently inefficient system gives us the ability to deal with the natural variability of the diurnal rhythms of light and temperature.
    • The diurnal rhythm of cortisol secretion in the horse peaks at approximately 0600 h and is least at approximately 1800 h.
  • 2.1 Astronomy Of or resulting from the daily rotation of the earth.
    More example sentences
    • Magnetism, in other words, caused the Earth's Copernican diurnal rotation.
    • In poetic form, Aryabhata stated that the earth's diurnal rotation on its axis produced the daily rising and setting of planets and stars.
    • Right ascension makes it easy to use the apparent diurnal rotation of the celestial sphere as a means to telling time.



More example sentences
  • Experimenters have established the use of a time-compensated sun-compass by homing pigeons and diurnally migrating songbirds.
  • Males fly readily both diurnally and nocturnally.
  • Nocturnal migrants following coasts and diurnally mobile individuals may also be channeled into those peninsular areas.


late Middle English (as a term in astronomy): from late Latin diurnalis, from Latin diurnus 'daily', from dies 'day'.

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