Definition of diurnal in English:

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Pronunciation: /dīˈərnl/


1Of or during the day.
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.
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.
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.
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.



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'.

Words that rhyme with diurnal

colonel, eternal, external, fraternal, infernal, internal, journal, kernel, maternal, nocturnal, paternal, supernal, vernal

For editors and proofreaders

Syllabification: di·ur·nal

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