1. 白昼的;白天的;日间活动的
Diurnal means happening or active during the daytime.

1. of or belonging to or active during the day

e.g. diurnal animals are active during the day
diurnal flowers are open during the day and closed at night
diurnal and nocturnal offices

2. having a daily cycle or occurring every day

e.g. diurnal rotation of the heavens