Diurnal

Diurnal may mean:

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• in biology, diurnal refers to animals that are active in the daytime. This definition may also apply to plants. Compare with nocturnal or crepuscular.
• in meteorology, diurnal means daily, especially pertaining to actions which are completed in 24 hours and are repeated every 24 hours; this can be seen in the diurnal temperature variation. An alternative word for diurnal in this sense is diel.
• in astronomy, diurnal motion refers to the apparent motion of stars around the Earth, caused by the Earth's rotation around its axis.