diurnal

[dahy-ur-nl]

adjective

1. of or relating to a day or each day; daily.

2. of or belonging to the daytime (nocturnal ).

3. Botany.,  showing a periodic alteration of condition with day and night, as certain flowers that open by day and close by night.

4. active by day, as certain birds and insects (nocturnal ).

noun

1. Liturgy.,  a service book containing offices for the daily hours of prayer.

2. Archaic.,  a diary.

3. Archaic.,  a newspaper, especially a daily one.

diurnal

/ daɪˈɜːnəl /

adjective

1. happening during the day or daily

2. (of flowers) open during the day and closed at night

3. (of animals) active during the day Compare nocturnal

noun

1. a service book containing all the canonical hours except matins

diurnal

1. 1. Occurring once in a 24-hour period; daily.

   2. Having a 24-hour cycle. The movement of stars and other celestial objects across the sky are diurnal.

2. Most active during the daytime. Many animals, including the apes, are diurnal.

3. Having leaves or flowers that open in daylight and close at night. The morning glory and crocus are diurnal.

4. Compare nocturnal

Other Word Forms

• diurnally adverb
• diurnalness noun
• transdiurnal adjective
• undiurnal adjective
• undiurnally adverb

Word History and Origins

Origin of diurnal¹

1400–50; late Middle English < Latin diurnālis, equivalent to diurn ( us ) daily + -ālis -al ¹

Word History and Origins

Origin of diurnal¹

C15: from Late Latin diurnālis, from Latin diurnus, from diēs day

Example Sentences

It is not rare in spring to have a large diurnal range but it is unusual just how dry and sunny it has been lately.

From BBC

Despite the warmth in the daytime, this has been at odds with the night-time temperatures with a huge difference between - what weather forecasters call diurnal range.

From BBC

Wilder’s drama, offering a guided tour of an ordinary town going about its diurnal business, reminds us, through the inescapable shadow of mortality, of what we have in common.

From Los Angeles Times

Yellow-bellied marmots are an excellent study system because they are diurnal, or active during the day, and they have an address.

From Salon

The 12 diurnal tiger beetle species that the researchers included in the study are evidence of this.

From Science Daily

Related Words

• constantly 
• day-to-day 
• everyday 
• often 
• periodic 
• regular 
• regularly 
• routine