Relating to the daytime; belonging to the period of
daylight, distinguished from the night; – opposed to nocturnal; as,
diurnal heat; diurnal hours.

Daily; recurring every day; performed in a day; going
through its changes in a day; constituting the measure of a day; as, a
diurnal fever; a diurnal task; diurnal aberration, or diurnal parallax;
the diurnal revolution of the earth.

Opening during the day, and closing at night; – said of
flowers or leaves.

Active by day; – applied especially to the eagles and
hawks among raptorial birds, and to butterflies (Diurna) among insects.

A daybook; a journal.

A small volume containing the daily service for the
“little hours,” viz., prime, tierce, sext, nones, vespers, and
compline.

A diurnal bird or insect.