Meaning : Of or belonging to or active during the day.
Example :
Diurnal animals are active during the day.
Diurnal flowers are open during the day and closed at night.
Diurnal and nocturnal offices.
Belonging to or active during the night.
Nocturnal animals are active at night.Meaning : Having a daily cycle or occurring every day.
Example :
Diurnal rotation of the heavens.