Definition of "diurnal" in English

adjective

1. Happening or occurring during daylight, or primarily active during that time.

   • Most birds are diurnal.

2. (botany) Said of a flower that is open, or releasing its perfume during daylight hours, but not at night.

3. Having a daily cycle that is completed every 24 hours, usually referring to tasks, processes, tides, or sunrise to sunset; circadian.

4. (uncommon) Done once every day; daily, quotidian.

5. (archaic) Published daily.

noun

1. A flower that opens only in the day.

2. (Catholicism) A book containing canonical offices performed during the day, hence not matins.

3. (archaic) A diary or journal.

4. (archaic) A daily news publication.