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1. Relating to or occurring in a 24-hour period; daily.
2. Occurring or active during the daytime rather than at night: diurnal animals.
3. Botany Opening during daylight hours and closing at night.
1. A book containing all the offices for the daily canonical hours of prayer except matins.
2. Archaic
a. A diary or journal.
b. A daily newspaper.

[Middle English, from Late Latin diurnālis, from Latin diurnus, from diēs, day; see dyeu- in Indo-European roots.]

di·ur′nal·ly adv.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
References in classic literature ?
Martin, from the fact of a great number of gentlemen on the ground below, immediately proceeding to cry 'Butcher!' in imitation of the tone in which that useful class of society are wont, diurnally, to make their presence known at area railings.
This phenomenon is called protogyny, diurnally synchronous dichogamy common when warm weather prevails during flowering.Spraying flowers with sulphur will not reduce the blossom drop.
Following previous research that demonstrated that feral hogs were more active during crepuscular and nocturnal periods, we predicted that hogs in northern Texas would also be more active during nocturnal periods, spending more time in areas providing cover diurnally and in more open land nocturnally when mobile.
We used radiotelemetry to study habitat use, spatial, and thermal ecology of three species of diurnally active lizards in the genus Micrulophus.
Balancing this inclusiveness against keeping the volume portable required judicious choices favouring visible (e.g., macroscopic, diurnally active, terrestrial, boat-, shipboard-, and coastal zone-accessible) taxa and species either endemic to the Arctic or especially characteristic of northern high latitudes.
During September and October 2014, we euthanized and necropsied 22 toads found hydrating or otherwise diurnally active near the TERF buildings.
"The results show separate effects of the endogenous circadian system, the behavioral cycle, and circadian misalignment on insulin sensitivity and ?-cell responsivity with relevance for daily glucose regulation in diurnally active people as well as night-shift workers," the authors write.
There was one observation of a diurnally active wombat (11 am in early December 2016) (Murphy pers.
In diurnally active patients, angina, acute MI, sudden cardiac death, and ischemic and hemorrhagic stroke occur more frequently during the initial 3-5 h of morning activity than at any other time of the day or night.
The same trend was seen in the diurnally aerated tanks, which exhibited a final D[O.sub.2] concentration of 2.15 [+ or -] 1.00 mg [L.sup.-1] (Figure 1).
Among taxa that contacted the bones, the birds and the domesticated cat were active diurnally. The only exceptions to all bird activity being diurnal were two visits by song sparrow and two visits by unknown Passerines during the crepuscular (twilight) hours.
This fishery involves 115 small trawlers (mostly <10 m and 110 kW) diurnally targeting school prawns, Metapenaeus macleayi (all <25 mm carapace length; CL) mostly during the Austral summer for annual catches of 400 t per annum valued at almost AUD $3 million.